Create branch-notes directory by default in user's home dir.
Create branch-notes directory by default in user's home dir.

It is a bit cumbersome to have to set the environment variable for the
notes directory. Instead it makes a lot more sense to simply default to
the user's home directory and use the environment variable only if it is
set.

ddddavidmartin/branch-notes,ddddavidmartin/branch-notes