csharp: fix some build warnings related with incorrect and missing documentation

csharp: fix some build warnings related with incorrect and missing documentation

Summary:
Some parameter names, tag names and cref identifiers in the documentation were
incorrect and causing warnings during compilation.
There were also warnings related with missing documentation in publicly
visible elements in the manual binding.

This commit fixes these incorrections and adds documentation to the manual
binding in order to solve these compilation warnings.

Warnings related with missing documentation in `.eo` files are still present.

Test Plan: Just compile with mono binding.

Reviewers: lauromoura, felipealmeida, segfaultxavi

Reviewed By: segfaultxavi

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D9243