[docs] Move socket options from API.md to a separate document

[maxsharabayko]

API.md document is very overloaded and not conveniently structured.
SRT socket options should be moved to a separate document similar to statistics.md with a similar summary table.

The API.md file contains a full list of socket options, which is purely readable and does not allow to reference a certain socket option in discussions. Consider moving the list to a separate document APISocketOptions.md with a structure like in the statistics.md.
Move the options section from API.md to APISocketOptions.md. Merge all per-socket tables with all their columns (OptName, Since, Binding, Type, etc.) into a single table. Each socket option should have a link to the description of the option (see statistics.md).