README.md: Document the syntax used in the README

Explain that the file is written in Markdown, and link to the Markdown
spec and GitHub's markup parsing docs.

After adjusting README.md in my text editor, I compared my working
directory with the index using:

  $ git diff

That looked reasonable, so I committed all the modifications using:

  $ git commit --all

The `--all` option tells Git to automatically stage any modifications
or deletions.  I could have used the following:

  $ git add README.md
  $ git commit

and achieved the same result.  Some people like to stage changes
explicitly, and some like to stage them automatically.  Pick whichever
works best for you.

diff --git a/README.md b/README.md
index 8cd0c73141ed545f37da1417eed91a0480f026f9..bbd45fbf047a42e9ebd6005debf1e486644dfce9 100644 (file)
--- a/README.md
+++ b/README.md
@@ -1,4 +1,13 @@
 Show how project development generally works in [Git][].
 
+Markup
+======
+
+This file is written in [Markdown][], a popular markup language.  The
+`.md` extension is a hint so renderers like [GitHub][] can format it
+appropriately.
+
 
 [Git]: http://www.git-scm.com/
+[Markdown]: http://daringfireball.net/projects/markdown/
+[GitHub]: https://github.com/github/markup#markups