Add Custom Dictionary Words as a vim til.

README.md

@@ -226,6 +226,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 ### vim
 
 - [Absolute And Relative Line Numbers](vim/absolute-and-relative-line-numbers.md)
+- [Add Custom Dictionary Words](vim/add-custom-dictionary-words.md)
 - [Alternate Files With vim-rails](vim/alternate-files-with-vim-rails.md)
 - [Amend Commits With Fugitive](vim/amend-commits-with-fugitive.md)
 - [The Black Hole Register](vim/the-black-hole-register.md)

vim/add-custom-dictionary-words.md

@@ -0,0 +1,12 @@
+# Add Custom Dictionary Words
+
+When editing a file with `spell` turned on, you may find vim highlighting
+some of your content in red. This red highlighting indicates a misspelling.
+Sure, these words technically aren't going to show up in something like the
+Merriam-Webster dictionary, but as far as you are concerned, they are words.
+They are part of your internal, shared language. The word *admin* is a great
+example. Why not just tell vim once and for all that such words are valid.
+
+You can do just that by moving your cursor over the *misspelled* word and
+hitting `zg`. That will add it to the `spellfile`, a list of words, which
+vim includes in its spell checking.