Added instructions: contains preface for "userbashrc"

install.sh: now creates the file userbashrc in the modules section
    moves the existing .bashrc to ~/.config/terrorshell/modules/userbashrc so that all pre existing
    aliases will persist
templates/bashrc: added userbashrc to the list of modules
TODO Learn how commit messages work, and proper practice for push's
TODO check existing bashrc for conflicting alias names
We cant it is echoed to the instruction file, but I cant create a file called userbashrc in the git repo or else it will replace the existing one when you update terrorshell. I could have added it to the install script I suppose.