[bobthefish] Add config options to readme.

README.md

@@ -45,6 +45,18 @@ This theme is based loosely on [agnoster][agnoster].
  * Abbreviated project-relative path
 
 
+### Configuration
+
+You can override some default options in your `config.fish`:
+
+    set -g theme_display_git no
+    set -g theme_display_hg yes
+    set -g theme_display_virtualenv no
+    set -g theme_display_ruby no
+    set -g theme_display_user yes
+    set -g default_user your_normal_user
+
+
 [screenshot]: http://i.0x7f.us/bobthefish.png
 [patching]:   https://powerline.readthedocs.org/en/latest/fontpatching.html
 [fonts]:      https://github.com/Lokaltog/powerline-fonts