Fix documentation instructions

Corrected the sphinx installation instructions to match the instructions in user_guide_src/README.rst
Signed-off-by:James L Parry <jim_parry@bcit.ca>
Better Issue report writeup

Documentation: contributing to CodeIgniter...
Added a reminder about issues vs support, and some tips for a good issue report.
This was suggested by a user on the forum, and seems like a good idea.
Signed-off-by:James L Parry <jim_parry@bcit.ca>