Update instructions on updating vimrc (#614)

README.md

@@ -63,8 +63,10 @@ If you have vim aliased as `vi` instead of `vim`, make sure to either alias it:
 Just do a git rebase!
 
     cd ~/.vim_runtime
+    git reset --hard
+    git clean -d --force
     git pull --rebase
-    python update_plugins.py
+    python update_plugins.py  # use python3 if python is unavailable
 
 
 ## Some screenshots

install_awesome_parameterized.sh

@@ -4,7 +4,10 @@ set -e
 echo 'Installing Awesome Vim from '$1
 cd $1
 
-VIMRC="set runtimepath+=$1
+VIMRC="\" DO NOT EDIT THIS FILE
+\" Add your own customizations in $1/my_configs.vim
+
+set runtimepath+=$1
 
 source $1/vimrcs/basic.vim
 source $1/vimrcs/filetypes.vim

install_awesome_vimrc.sh

@@ -3,7 +3,10 @@ set -e
 
 cd ~/.vim_runtime
 
-echo 'set runtimepath+=~/.vim_runtime
+echo '" DO NOT EDIT THIS FILE
+" Add your own customizations in ~/.vim_runtime/my_configs.vim
+
+set runtimepath+=~/.vim_runtime
 
 source ~/.vim_runtime/vimrcs/basic.vim
 source ~/.vim_runtime/vimrcs/filetypes.vim