Add Case-Insensitive Search as an ack til

Author: jbranchaud

README.md

@@ -10,7 +10,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 For a steady stream of TILs from a variety of rocketeers, checkout
 [til.hashrocket.com](https://til.hashrocket.com/).
 
-_520 TILs and counting..._
+_521 TILs and counting..._
 
 ---
 
@@ -42,6 +42,7 @@ _520 TILs and counting..._
 ### Ack
 
 - [ack --bar](ack/ack-bar.md)
+- [Case-Insensitive Search](ack/case-insensitive-search.md)
 - [List Available File Types](ack/list-available-file-types.md)
 
 ### Chrome

ack/case-insensitive-search.md

@@ -0,0 +1,18 @@
+# Case-Insensitive Search
+
+Use the `-i` flag to perform a case-insensitive search with `ack`.
+
+```bash
+$ ack -i easter
+
+ack/ack-bar.md
+3:The [`ack`](https://beyondgrep.com/) utility has a fun Easter egg that dumps
+
+postgres/configure-the-timezone.md
+18:Eastern time.
+```
+
+If you are a Vim user, you may be familiar with `smart-case`. The
+`--smart-case` option is a related Ack feature worth checking out.
+
+See `man ack` for more details.