Fix typos

In templates_static.rst:

    - Typo: stored -> store
    - Add the "About" link to the 4.1.2 template listing, for consistency

    In models.rst:

    - Add missing whitespace in list_display tuple

    In models.templates.rst:

    - Add linebreak, the comment in this code listing 'overflows' otherwise.
    - Move misplaced ` which messed up the output rendering

    In forms.rst:

    - Add whitespace in fields tuple

    In cookie.rst:

    - Remove 'how to' (or should it be changed to 'how to use'?)
    - Change 'how to explicitly used cookies' to 'how to explicitly use
      cookies'
    - Change 'thet' to 'that'
    - The code in the 10.9.1 hint results in a KeyError. Should we not use
    request.session.get('visits') instead of request.session['visits']?