Guide users to set user.name and/or user.email if missing from git config

[eamodio]

No description provided.

[rzhao271]

Adding verification-steps-needed since I'm not sure what the new behaviour should be.

Firstly, I was able to make a commit with a name but no email. GitHub allows this by writing name <> instead of name <someemail> in the log.

When both were missing, I remember getting an error, along with an option to view the log, where I can then see the "missing name" message.

[eamodio]

Yeah, you should get the following:

If either user.name or user.email is missing from your git configuration.