Re-Iterate, Fix Optimum Nvidia Benchmark and add Readme

[Anindyadeep]

• Solves issue Add a readme under each benchmark. #88
• Solves issue Update and re-iterate the missing parts of benchmarks.  #131

Checks:

• Checksetup.sh and bench.sh have Python files configured for both Mac and Linux and installation working.
• Check if int32 < int16 patterns follow.
• Check the log file name and where it is kept.
• Check if all precisions can be covered or not and if not put an issue.
• Check if all devices can be covered or not otherwise put an issue or find an issue (it's just memory issue and too slow, mentioned in Readme).
• Check the Benchmark README.

[nsosio]

LGTM