Merge with upstream

Author: ogr3

README.md

@@ -97,6 +97,7 @@ The symbols are as follows:
 ```sh
 if [ -f "$(brew --prefix)/opt/bash-git-prompt/share/gitprompt.sh" ]; then
   GIT_PROMPT_THEME=TruncatedPwd_WindowTitle
+  __GIT_PROMPT_DIR=$(brew --prefix)/opt/bash-git-prompt/share
   source "$(brew --prefix)/opt/bash-git-prompt/share/gitprompt.sh"
 fi
 ```

bash-git-prompt.rb

@@ -20,6 +20,7 @@ def caveats; <<-EOS.undent
     You should add the following to your .bashrc (or equivalent):
       if [ -f "$(brew --prefix bash-git-prompt)/share/gitprompt.sh" ]; then
         GIT_PROMPT_THEME=Default
+        __GIT_PROMPT_DIR=$(brew --prefix)/opt/bash-git-prompt/share
         source "$(brew --prefix bash-git-prompt)/share/gitprompt.sh"
       fi
     EOS