Add example of tuning RocksDB on NNI

[gxiaotian]

This PR adds example of tuning RocksDB on NNI as well as its English and Chinese documents.

[msftclas]

All CLA requirements met.

[QuanluZhang]

looks great! the first example for tuning system parameters

[xuehui1991]

Hello @gxiaotian seems there is some syntax error which could make the PR cannot pass the IT:

./examples/trials/systems/rocksdb-fillrandom/main.py:29:24: E999 SyntaxError: invalid syntax
    args = [f"--{k}={v}" for k, v in parameters.items()]
                       ^
1     E999 SyntaxError: invalid syntax

[gxiaotian]

Hi @xuehui1991 , the script runs well in my experiments. I don't know why flake8 treats it a syntax error. Do you have any clue? Thank you!

[xuehui1991]

Hi @xuehui1991 , the script runs well in my experiments. I don't know why flake8 treats it a syntax error. Do you have any clue? Thank you!

Hello @gxiaotian Could you install flake8 in your environment and reproduce this error?

[gxiaotian]

Hi @xuehui1991 , the script runs well in my experiments. I don't know why flake8 treats it a syntax error. Do you have any clue? Thank you!

Hello @gxiaotian Could you install flake8 in your environment and reproduce this error?

Hi @xuehui1991 , great thanks for your kind help. flake8 is my major linter for python, but I can't reproduce this error. Here are the details about my flake8: 3.7.8 (mccabe: 0.6.1, pycodestyle: 2.5.0, pyflakes: 2.1.1) CPython 3.6.8 on Linux , and follows are the check results.

[xuehui1991]

Hi @xuehui1991 , the script runs well in my experiments. I don't know why flake8 treats it a syntax error. Do you have any clue? Thank you!

Hello @gxiaotian Could you install flake8 in your environment and reproduce this error?

Hi @xuehui1991 , great thanks for your kind help. flake8 is my major linter for python, but I can't reproduce this error. Here are the details about my flake8: 3.7.8 (mccabe: 0.6.1, pycodestyle: 2.5.0, pyflakes: 2.1.1) CPython 3.6.8 on Linux , and follows are the check results.

Hello @chicm-ms, could you help to check the flake version of the pipeline? Thank you~