Add Case-Aware Substitution With vim-abolish as a vim til.

README.md

@@ -147,6 +147,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Alternate Files With vim-rails](vim/alternate-files-with-vim-rails.md)
 - [The Black Hole Register](vim/the-black-hole-register.md)
 - [Buffer Time Travel](vim/buffer-time-travel.md)
+- [Case-Aware Substitution With vim-abolish](vim/case-aware-substitution-with-vim-abolish.md)
 - [Case-Insensitive Substitution](vim/case-insensitive-substitution.md)
 - [Check Your Current Color Scheme](vim/check-your-current-color-scheme.md)
 - [Close the Current Buffer](vim/close-the-current-buffer.md)

vim/case-aware-substitution-with-vim-abolish.md

@@ -0,0 +1,22 @@
+# Case-Aware Substitution With vim-abolish
+
+Substitution in vim is, by default, case-sensitive. Adding the `i` `s-flag`
+makes it case-insensitive.
+[`vim-abolish`](https://github.com/tpope/vim-abolish), on the other hand, lets
+you perform a case-insensitive substitution that preserves three case
+variants (foo, Foo, and FOO). Substitution with `vim-abolish` can be
+performed with `Subvert` or `S`.
+
+For instance, `:%S/blog/article/g` will turn
+
+```
+blog Blog bLOg BLOG
+```
+
+into
+
+```
+article Article bLOg ARTICLE
+```
+
+Install `vim-abolish` and see `:h Subvert` for more details.