feature: add git add -p to git module

modules/git/README.md

@@ -259,6 +259,10 @@ zstyle ':prezto:module:git:alias' skip 'yes'
   - `gRs` displays information about a given remote.
   - `gRb` opens a remote on [GitHub][3] in the default browser.
 
+### Stage
+
+  - `gap` stage changes interactively
+
 ### Stash
 
   - `gs` stashes the changes of the dirty working directory.

modules/git/alias.zsh

@@ -238,6 +238,10 @@ if ! zstyle -t ':prezto:module:git:alias' skip 'yes'; then
   alias gsS='git stash save --patch --no-keep-index'
   alias gsw='git stash save --include-untracked --keep-index'
 
+  # Stage (a)
+  alias gap='git add -p'
+
+
   # Submodule (S)
   alias gS='git submodule'
   alias gSa='git submodule add'