Rename docs/*.md => docs/*.txt

The documentation uses features of Python-Markdown that are not supported on
GitHub and it's better to get a source view of the docs anyway. For example,
that way comments and bug reports can reference a specific line of a file.

Of course, it makes sense for Github to render the README, so that is left
with the `.md` file extension.

1 files changed, 48 insertions, 0 deletions

diff --git a/docs/extensions/extra.txt b/docs/extensions/extra.txt
new file mode 100644
index 0000000..adafe07
--- /dev/null
+++ b/docs/extensions/extra.txt
@@ -0,0 +1,48 @@
+title:      Extra Extension
+prev_title: Extensions
+prev_url:   index.html
+next_title: Abreviation Extension
+next_url:   abbreviations.html
+
+Python-Markdown Extra
+=====================
+
+Summary
+-------
+
+A compilation of various Python-Markdown extensions that (mostly) imitates
+[PHP Markdown Extra](http://michelf.com/projects/php-markdown/extra/).
+
+The supported extensions include:
+
+* [Abbreviations](abbreviations.html)
+* [Attribute Lists](attr_list.html)
+* [Definition Lists](definition_lists.html)
+* [Fenced Code Blocks](fenced_code_blocks.html)
+* [Footnotes](footnotes.html)
+* [Tables](tables.html)
+* [Smart Strong](smart_strong.html)
+
+See each individual extension for syntax documentation. Extra and all its 
+supported extensions are included in the standard Markdown library.
+
+Usage
+-----
+
+From the Python interpreter:
+
+    >>> import markdown
+    >>> html = markdown.markdown(text, ['extra'])
+
+In the unlikely event that one or more of the supported extensions are not
+available for import, Markdown will simply continue without that
+extension. If you would like to be notified of such failures,
+you may set Python-Markdown's logger level to "WARN".
+
+There may be [additional extensions](index.html) that are distributed with
+Python-Markdown that are not included here in Extra. The features 
+of those extensions are not part of PHP Markdown Extra, and 
+therefore, not part of Python-Markdown Extra. If you really would 
+like Extra to include additional extensions, we suggest creating 
+your own clone of Extra under a different name 
+(see the [Extension API](api.html)).