Update examples to refer to contrib/source-build.sh

[jasoncodes]

The install script output and generated example .freshrc file should reference contrib/source-build.sh. When $SHELL is bash we should output something like the following:

fresh freshshell/fresh bin/fresh --bin

fresh freshshell/fresh contrib/source-build.sh --file=~/.bash_profile
fresh freshshell/fresh contrib/source-build.sh --file=~/.bashrc

We should also output a different message if we did not generate a .freshrc file that omits mentioning initial setup and only outputs the message about opening a new shell for everything to take effect.

[jasoncodes]

I think we could also get away with removing the default ~/.bashrc if it’s a file and the contents match /etc/skel/.bashrc. This would streamline setup on new Debian/Ubuntu user accounts.

[jasoncodes]

It might also make sense for the install script to create ~/.dotfiles if it doesn’t exist, create ~/.dotfiles/freshrc if it doesn’t exist (instead of the current ~/.freshrc), then create the ~/.freshrc symlink to ~/.dotfiles/freshrc before invoking fresh for the first time. This would make the recommended setup more obvious. We could also go ahead and create an initial commit if ~/.dotfiles is not yet a git repo.

[jasoncodes]

It might be worth revisiting the example section too to see if we can make it more obvious as to what each of the example lines does. Maybe add a link to the relevant documentation section for each.