Added github-links to the .sublime-completions files

It's more convenient to click a link, rather than opening the Packages folder to inspect the files.
The link is to the master branch of LaTeXTools.

docs/completions.md

@@ -4,7 +4,7 @@
 
 By default, ST provides a number of snippets for LaTeX editing; the LaTeXTools plugin adds a few more. You can see what they are, and experiment, by selecting **Tools | Snippets | LaTeX** and **Tools | Snippets | LaTeXTools** from the menu.
 
-In addition, the LaTeXTools plugin provides useful completions for both regular and math text; check out files `LaTeX.sublime-completions` and `LaTeX math.sublime-completions` in the LaTeXTools directory for details. Some of these are semi-intelligent: i.e. `bf` expands to `\textbf{}` if you are typing text, and to `\mathbf{}` if you are in math mode. Others allow you to cycle among different completions: e.g. `f` in math mode expands to `\phi` first, but if you hit Tab again you get `\varphi`; if you hit Tab a third time, you get back `\phi`.
+In addition, the LaTeXTools plugin provides useful completions for both regular and math text; check out files [`LaTeX.sublime-completions`](https://github.com/SublimeText/LaTeXTools/blob/master/LaTeX.sublime-completions) and [`LaTeX math.sublime-completions`](https://github.com/SublimeText/LaTeXTools/blob/master/LaTeX%20math.sublime-completions) in the LaTeXTools directory for details. Some of these are semi-intelligent: i.e. `bf` expands to `\textbf{}` if you are typing text, and to `\mathbf{}` if you are in math mode. Others allow you to cycle among different completions: e.g. `f` in math mode expands to `\phi` first, but if you hit Tab again you get `\varphi`; if you hit Tab a third time, you get back `\phi`.
 
 ## LaTeX-cwl support