Add Whole Line Auto Completion as a vim til.

README.md

@@ -79,6 +79,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Tabs To Spaces](vim/tabs-to-spaces.md)
 - [The Vim Info File](vim/the-vim-info-file.md)
 - [View Commit History of a File](vim/view-commit-history-of-a-file.md)
+- [Whole Line Auto-Completion](vim/whole-line-auto-completion.md)
 - [Wrap With Some Room](vim/wrap-with-some-room.md)
 
 ### zsh

vim/whole-line-auto-completion.md

@@ -0,0 +1,16 @@
+# Whole Line Auto-Completion
+
+To get whole line auto-completion in Vim, you don't need a fancy plugin. It
+is built right in. There is a sub-mode of insert mode called *X mode* that
+allows you to do various kinds of special insertions. The `ctrl-x ctrl-l`
+binding corresponds to whole line completion. So, if you start typing a few
+characters and then (while still in insert mode) hit `ctrl-x ctrl-l` you
+will see a completed line that matches the initial characters you typed as
+well as a list of subsequent matches. You can cycle through the matches
+using `ctrl-n` and `ctrl-p` (going forward and backward, respectively).
+
+The completion is done based on the configured completion sources.
+Generally, the completion sources will include the current buffer, other
+loaded and unloaded buffers, plus others. You can see which sources are
+configured with `:set complete?` and read more about the completion
+configuration at `:h 'complete'`.