Clarify "Starting as a Contributor" document

[Ali Çehreli]

This page is very good:

   https://wiki.dlang.org/Starting_as_a_Contributor

I need clarifications:

1) Should we change all

   git push -f ...

commands there with

   git push --force-with-lease ...

2) Can you please explain the last sentence of this part:

<quote>
If the pull request is for a bug fix, the commit message should have the 
format "fix issue 1234". This enables the dlang-bot to automatically 
pick up the issue from Bugzilla and post it as a comment on the PR. If 
the PR is already open, then a git rebase is necessary followed by a 
force push. During the rebase, the commit message should be renamed to 
match the one specified.
</quote>

What is "the commit message"? What is "the one specified"?

3) Does Dlang-Bot already do the following or should the contributor do 
it manually?

"Pull request descriptions should contain a hyperlink to the Bugzilla 
issue that is being fixed. This is usually added at the end of the 
description."

Thank you,
Ali