Add Breaking The Undo Sequence as a vim til.

README.md

@@ -291,6 +291,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Amend Commits With Fugitive](vim/amend-commits-with-fugitive.md)
 - [Beginning And End Of Previous Change](vim/beginning-and-end-of-previous-change.md)
 - [The Black Hole Register](vim/the-black-hole-register.md)
+- [Breaking The Undo Sequence](vim/breaking-the-undo-sequence.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)

vim/breaking-the-undo-sequence.md

@@ -0,0 +1,34 @@
+# Breaking The Undo Sequence
+
+Generally, the sequence of undo-able actions is segmented by command. When
+entering Insert mode, everything typed until exiting Insert mode is part of
+a single undo-able segment. If you are going to be typing in Insert mode for
+a while though, you may want to break it up a bit. Without leaving Insert
+mode, hit `ctrl-g u` to mark a break in the sequence of undos.
+
+For example, starting in Normal mode and then typing
+`iabc<CTRL-G>udef<CTRL-G>ughi<ESC>` will leave the buffer with:
+
+```
+abcdefghi
+```
+
+Hitting `u` once will leave the buffer with:
+
+```
+abcdef
+```
+
+Hitting `u` again:
+
+```
+abc
+```
+
+Hitting `ctrl-r`:
+
+```
+abcdef
+```
+
+See `:h i_CTRL-G_u` for more details.