update .zshrc

so many changes. i think i rewrote it a few times since my last
commit on this file.
add INSTALL.sh

INSTALL.sh creates symbolic links to the dot files in this repository.
$HOME/.zshrc will become a symbolic link to .zshrc in this repository,
etc.

the symbolic links are created with force(removing any file that may have
been there before).

$ sh INSTALL.sh
add new pry command. "X times .."

regexp commands in pry are fun. "X times .." is a regexp command
that can execute commands via a shell.

common thing I use it for:
pry(main)> 4 times time ruby myscript.rb
add README.md