Have "Edit on GitHub" point to master instead of gh-pages

Summary:
If someone clicks on `Edit on GitHub` to edit a doc for a pull request, for example,
then we should point to `master` instead of `gh-pages`.

> Also fixed some Windows-based line endings. From CRLF to LF.

Test Plan: https://www.facebook.com/pxlcld/pvV2

Reviewers: IslamAbdelRahman, lgalanis, sdong

Reviewed By: sdong

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D63435

docs/_includes/doc.html

@@ -1,25 +1,25 @@
-<div class="post">
-  <header class="post-header">
-    <h1 class="post-title">{% if include.truncate %}<a href="{{ site.url }}{{ site.baseurl }}{{ page.url }}">{{ page.title }}</a>{% else %}{{ page.title }}{% endif %}</h1>
-  </header>
-
-  <article class="post-content">
-   {% if include.truncate %}
-      {% if page.content contains '<!--truncate-->' %}
-        {{ page.content | split:'<!--truncate-->' | first }}
-        <div class="read-more">
-          <a href="{{ site.url }}{{ site.baseurl }}{{ page.url }}" >
-            ...Read More
-          </a>
-        </div>
-      {% else %}
-        {{ page.content }}
-      {% endif %}
-    {% else %}
-      {{ content }}
-
-      <p><a class="edit-page-link" href="https://github.com/{{ site.ghrepo }}/tree/gh-pages/{{ page.path }}" target="_blank">Edit on GitHub</a></p>
-    {% endif %}
-  </article>
-  {% include doc_paging.html %}
-</div>
+<div class="post">
+  <header class="post-header">
+    <h1 class="post-title">{% if include.truncate %}<a href="{{ site.url }}{{ site.baseurl }}{{ page.url }}">{{ page.title }}</a>{% else %}{{ page.title }}{% endif %}</h1>
+  </header>
+
+  <article class="post-content">
+   {% if include.truncate %}
+      {% if page.content contains '<!--truncate-->' %}
+        {{ page.content | split:'<!--truncate-->' | first }}
+        <div class="read-more">
+          <a href="{{ site.url }}{{ site.baseurl }}{{ page.url }}" >
+            ...Read More
+          </a>
+        </div>
+      {% else %}
+        {{ page.content }}
+      {% endif %}
+    {% else %}
+      {{ content }}
+
+      <p><a class="edit-page-link" href="https://github.com/{{ site.ghrepo }}/blob/master/docs/{{ page.path }}" target="_blank">Edit on GitHub</a></p>
+    {% endif %}
+  </article>
+  {% include doc_paging.html %}
+</div>