add configuration file

[toutdesuite]

Signed-off-by: toutdesuite guizhiluo2014@163.com

What is changed?

This PR adds configuration file to dev.

Any related PRs or issues?

N/A

Which version does your change affect?

dev

[toutdesuite]

@dcalvin PTAL, thanks!

[dcalvin]

@anotherrachel PTAL.

[anotherrachel]

This PR adds a configuration file, but actually some of the configuration items are covered.
For example, /configuration/tikv-server/configuration-file/#security and /configure/security/ somewhat overlap.

Also, this PR links back to Pingcap.com. The configuration flags part is also covered in TiKV.org.

In TiKV/docs repo, the config docs are categorized into 11 topics and displayed separately:

• namespace.md
• region-merge.md
• store-limit.md
• titan.md
• coprocessor-config.md (not added)
• grpc-config.md (not added)
• pd-scheduler-config.md (not added)
• raftstore-config.md (not added)
• rocksdb-option-config.md
• security-config.md
• storage-config.md (not added)

For more information, see here.

However, in PingCAP/docs repo, all the configuration items of TiKV are introduced in 1 doc.

That means, to update TiKV configuration file, we need extra steps:

1. Add coprocessor-config.md, grpc-config.md, pd-scheduler-config.md, raftstore-config.md, storage-config.md to TiKV/website.
2. Compare configuration items in PingCAP/docs repo with that in TiKV/website repo (pay attention to newly added ones).
3. Update configuration items accordingly.

Also, the existing config docs in TiKV/website are kept under Tasks/Configure whereas in PingCAP/docs under Reference/Configuration. Perhaps that's the reason why there are 5 config docs left unadded, because they are introduced reference-wise.

FYI @dcalvin