Add Readme files for javascript examples
Add README.md files as documentation on supposed usage of javascript
examples:
javascript-sensors-viewer
sensor-graph
sensors-viewer
A README.md file is added as well on the root folder for examples.
ADD
examples/README.md
+# Examples
+
+This is a collection of examples that shows how to interact with Astarte in common use cases.
+
+## JavaScript examples
+
+- [javascript-sensors-viewer](javascript-sensors-viewer): sample web page in vanilla JavaScript to
+ show available sensors of a device and their data.
+- [sensors-viewer](sensors-viewer): sample web page in React to show available sensors of a device
+ and their data.
+- [sensor-graph](sensor-graph): sample web page in React to plot data coming from a sensor of a
+ device.

ADD
examples/javascript-sensors-viewer/README.md
+# Sensors Viewer example
+
+This is a sample web page made in vanilla JavaScript that you can use to show available sensors of a
+device and their data.
+
+You can follow the walkthrough below if you wish to try it out: you will first simulate a device
+that streams data from its sensors to Astarte, then use this web page to retrieve an overview of the
+device sensors from Astarte.
+
+## Prerequisites
+
+For this example you should:
+
+1. have an Astarte instance up and running with a realm you have access to
+2. install the [example interfaces](../../standard-interfaces/) in the realm
+3. register a device that will use those interfaces in the realm; be sure to note down its device ID
+ and Credentials Secret
+4. modify the `configuration` variable in `index.html` and specify: the `endpoint` of the Astarte
+ instance, the `realm` you chose, a valid JWT `token` that can be used to communicate with
+ AppEngine, the `device` ID your registered.
+
+## Docker walkthrough
+
+You can use Astarte's `stream-qt5-test` to emulate an Astarte device and generate a `datastream`:
+
+```sh
+docker run --net="host" -e "DEVICE_ID=<device_id>" -e "PAIRING_HOST=<pairing_host>" -e "REALM=<realm>" -e "AGENT_KEY=<agent_key>" -e "IGNORE_SSL_ERRORS=true" astarte/astarte-stream-qt5-test:0.11.4
+```
+
+where `device_id` is the device you registered, `pairing_host` is the Astarte endpoint for the
+Pairing APIs, `realm` is the name of your realm, `agent_key` is the valid JWT token of an Agent.
+
+If all went well, `stream-qt5-test` should now be streaming data to Astarte.
+
+Going back to the web page of this example, you can input the device ID to request an overview of
+the device sensors and their data.
+
+![Sensors Viewer example, requesting the overview of a device sensors and their data](../images/javascript-sensors-viewer-stream-test.png)

ADD
examples/sensor-graph/README.md
+# Sensor Graph example
+
+This is a sample web page made in React that you can use to plot data coming from a sensor of a
+device.
+
+You can follow the walkthrough below if you wish to try it out: you will first simulate a device
+that streams data from its sensors to Astarte, then use this web page to plot the data.
+
+## Prerequisites
+
+For this example you should:
+
+1. have an Astarte instance up and running with a realm you have access to
+2. install the [example interfaces](../../standard-interfaces/) in the realm
+3. register a device that will use those interfaces in the realm; note down its device ID and
+ Credentials Secret
+4. have [NodeJS](https://nodejs.org/) installed on your machine and serve this web page with
+ ```sh
+ npm install
+ npm run start
+ ```
+
+If all went well, you should see a form where you can supply:
+
+- the base URL of the Astarte instance
+- the name of your realm
+- a valid JWT access token for the realm that can be used to communicate with AppEngine
+
+## Docker walkthrough
+
+You can use Astarte's `stream-qt5-test` to emulate an Astarte device and generate a `datastream`:
+
+```sh
+docker run --net="host" -e "DEVICE_ID=<device_id>" -e "PAIRING_HOST=<pairing_host>" -e "REALM=<realm>" -e "AGENT_KEY=<agent_key>" -e "IGNORE_SSL_ERRORS=true" astarte/astarte-stream-qt5-test:0.11.4
+```
+
+where `device_id` is the device you registered, `pairing_host` is the Astarte endpoint for the
+Pairing APIs, `realm` is the name of your realm, `agent_key` is the valid JWT token of an Agent.
+
+If all went well, `stream-qt5-test` should now be streaming data to Astarte.
+
+Going back to the web page of this example, you can input the device ID to request a plot of the
+device data.
+
+![Sensor Graph example, requesting the plot of a device sensor](../images/sensor-graph.png)

ADD
examples/sensors-viewer/README.md
+# Sensors Viewer example
+
+This is a sample web page made in React that you can use to show available sensors of a device and
+their data.
+
+You can follow the walkthrough below if you wish to try it out: you will first simulate a device
+that streams data from its sensors to Astarte, then use this web page to retrieve an overview of the
+device sensors from Astarte.
+
+## Prerequisites
+
+For this example you should:
+
+1. have an Astarte instance up and running with a realm you have access to
+2. install the [example interfaces](../../standard-interfaces/) in the realm
+3. register a device that will use those interfaces in the realm; note down its device ID and
+ Credentials Secret
+4. have [NodeJS](https://nodejs.org/) installed on your machine and serve this web page with
+ ```sh
+ npm install
+ npm run start
+ ```
+
+If all went well, you should see a form where you can supply:
+
+- the base URL of the Astarte instance
+- the name of your realm
+- a valid JWT access token for the realm that can be used to communicate with AppEngine
+
+## Docker walkthrough
+
+You can use Astarte's `stream-qt5-test` to emulate an Astarte device and generate a `datastream`:
+
+```sh
+docker run --net="host" -e "DEVICE_ID=<device_id>" -e "PAIRING_HOST=<pairing_host>" -e "REALM=<realm>" -e "AGENT_KEY=<agent_key>" -e "IGNORE_SSL_ERRORS=true" astarte/astarte-stream-qt5-test:0.11.4
+```
+
+where `device_id` is the device you registered, `pairing_host` is the Astarte endpoint for the
+Pairing APIs, `realm` is the name of your realm, `agent_key` is the valid JWT token of an Agent.
+
+If all went well, `stream-qt5-test` should now be streaming data to Astarte.
+
+Going back to the web page of this example, you can input the device ID to request an overview of
+the device sensors and their data.
+
+![Sensors Viewer example, requesting the overview of a device sensors and their data](../images/sensors-viewer-stream-test.png)

Add Readme files for javascript examples

Add README.md files as documentation on supposed usage of javascript
examples:
- javascript-sensors-viewer
- sensor-graph
- sensors-viewer
A README.md file is added as well on the root folder for examples.

Signed-off-by: Davide Briani <davide.briani@ispirata.com>