fix typesetting issues

.. code-block:: bash

    $ git add doc/src/Howto_github.txt

    $ git add doc/src/JPG/tutorial\*.png

    $ git add doc/src/JPG/tutorial*.png

.. warning::

   Do not use *git commit -a* (or *git add -A*\ ).  The -a

   flag (or -A flag) will automatically include \_all\\_ modified or new files

   Do not use *git commit -a* (or *git add -A*\ ).  The -a flag (or -A

   flag) will automatically include **all** modified **and** new files

   and that is rarely the behavior you want.  It can easily lead to

   accidentally adding unrelated and unwanted changes into the repository.

   Instead it is preferable to explicitly use *git add*\ , *git rm*\ , *git mv*

   for adding, removing, renaming individual files, respectively, and then

   *git commit* to finalize the commit.  Carefully check all pending

   changes with *git status* before committing them.  If you find doing

   this on the command line too tedious, consider using a GUI, for example

   the one included in git distributions written in Tk, i.e. use *git gui*

   (on some Linux distributions it may be required to install an additional

   package to use it).

   accidentally adding unrelated and unwanted changes into the

   repository.  Instead it is preferable to explicitly use *git add*\ ,

   *git rm*\ , *git mv* for adding, removing, renaming individual files,

   respectively, and then *git commit* to finalize the commit.

   Carefully check all pending changes with *git status* before

   committing them.  If you find doing this on the command line too

   tedious, consider using a GUI, for example the one included in git

   distributions written in Tk, i.e. use *git gui* (on some Linux

   distributions it may be required to install an additional package to

   use it).

After adding all files, the change set can be committed with some

useful message that explains the change.

.. code-block:: bash

    $ git add Howto_github.txt

    $ git add JPG/tutorial_reverse_pull_request\*.png

    $ git add JPG/tutorial_reverse_pull_request*.png

    $ git commit -m "Updated text and images on reverse pull requests"

    $ git pull