R markdown link is not formatted blue when knitted to pdf
<p>for some reason no link in my R markdowns (rmd) is formatted blue. knitting the simple rmd below to pdf is leaving the text color black. only when hovering over it does one realize that it's actually a link. knitting it to html will make the link blue. of course I can use a latex wrapper but I wonder why that is?</p>

<blockquote>
  <p>sessionInfo()
  R version 3.3.0 (2016-05-03)
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  Running under: Windows 7 x64 (build 7601) Service Pack 1
  loaded via a namespace (and not attached):
   knitr_1.15</p>
</blockquote>

<p>RStudio 1.0.44</p>

<pre><code>---
title: "R Notebook"
output:
  pdf_document: default
  html_notebook: default
---

```{r, echo=F}
# tex / pandoc options for pdf creation
x &lt;- Sys.getenv("PATH")
y &lt;- paste(x, "E:\\miktex\\miktex\\bin", sep=";")
Sys.setenv(PATH = y)
```

[link](www.rstudio.com)
</code></pre>

<p><a href="https://i.stack.imgur.com/awos7.png" rel="noreferrer"><img src="https://i.stack.imgur.com/awos7.png" alt="enter image description here"></a></p>