Make how-to documentation update based on sprint practice

After #1732758: CodeSprint - Drupal Night in Ukraine before DrupalCamp Kyiv 2012 all the team decided - documentation is a main fail in convertion process time
So we need update master docs for http://groups.drupal.org/node/234783 write-up

Feel free to propose issues that have best practice

Own proposal from #1770284: [META] Drupal 8 with twig issue queue cleanup

• #1779152: Convert theme_fieldset to TWIG
• #1779034: Convert theme_field to twig
• #1778968: Convert theme_table to Twig