Mention that Git is an implicit dependency

This change is due to the persistent and pedantic complaints by the
user sitting by cip1e2.

README.md

@@ -5,8 +5,8 @@ A (exhaustive enough) _Algebra of Programming_ Summary
 correctness nor completeness.  Contributions and improvements are
 always appricaited.
 
-To build this document, it should suffice to have a basic LaTeX
-installation and then invoke
+To build this document, it should suffice to have a basic LaTeX and
+[Git](https://git-scm.com/) installation and then invoke
 
     $ pdflatex --shell-escape master.tex