Added documentation.

README.md

@@ -233,7 +233,6 @@ currently available are:
 
 * **aws** - The current AWS profile, if active (more info below)
 * **context** - Your username and host (more info below)
-* **vi_mode** - Vi editing mode (NORMAL|INSERT).
 * **dir** - Your current working directory.
 * **history** - The command number for the current line.
 * **ip** - Shows the current IP address.
@@ -248,6 +247,7 @@ currently available are:
 * **symfony2_tests** - Show a ratio of test classes vs code classes for Symfony2.
 * **symfony2_version** - Show the current Symfony2 version, if you are in a Symfony2-Project dir.
 * **time** - System time.
+* **vi_mode** - Vi editing mode (NORMAL|INSERT).
 * **virtualenv** - Your Python [VirtualEnv](https://virtualenv.pypa.io/en/latest/).
 * **vcs** - Information about this `git` or `hg` repository (if you are in one).
 
@@ -330,6 +330,26 @@ is count your source files and test files, and calculate the ratio between them.
 Just enough to give you a quick overview about the test situation of the project
 you are dealing with.
 
+#### VI-Mode Indicator
+
+This Segment shows the current mode of your ZSH. If you want to use your ZSH in
+VI-Mode, you need to configure it separatly in your `~/.zshrc`:
+
+    # VI-Mode
+    # general activation
+    bindkey -v
+    
+    # set some nice hotkeys
+    bindkey '^P' up-history
+    bindkey '^N' down-history
+    bindkey '^?' backward-delete-char
+    bindkey '^h' backward-delete-char
+    bindkey '^w' backward-kill-word
+    bindkey '^r' history-incremental-search-backward
+
+    # make it more responsive
+    export KEYTIMEOUT=1
+
 #### The 'vcs' Segment
 
 By default, the `vcs` segment will provide quite a bit of information. If you