Update getting_started.rst

In the event they don't have python installed, this may help.
Merge branch 'jcnorman-patch-4'
Update how_to_get_help.rst
Merge branch 'jcnorman-patch-3'
Fixing typos, markup.
Merge pull request #45 from vaab/patch-2

Fixing typos, markup.
updated ``Installation Procedure`` section to add several information.

- a quick description of each part just to know what to install
  - state that modules are addons for the server (which might not be clear to reader)
  - imply that tryton is a client and other client exists.
- removed the ``$`` because we want people to be able to cut and paste
- remaining typo: modules where incorrectly tryton_module instead of trytond_module...
- don't force virtual env, but recommend it.
- where to get list of modules.
- separate clearly each install commands.
Merge pull request #46 from vaab/patch-1

updated ``Installation Procedure`` section to add several information.