docs/index.rst fixup Sphinx warnings
docs/index.rst fixup Sphinx warnings

No functional changes, only Sphinx related corrections.

* Removing trailing whitespaces and useless empty lines.
* Removing trailing source code block marks which doesn't
  have any content to display as code.
* Intent all code blocks to one character intention.
* Correct to short title underlining.

HewlettPackard/python-ilorest-library,HewlettPackard/python-ilorest-library