pd-configuration-file: Docs for `max-request-bytes` is missing.

[dveeden]

Error Report

1. What is the URL/path of the document related to this issue?

• https://docs.pingcap.com/tidb/stable/pd-configuration-file
• https://github.com/tikv/pd/blob/147e9c041a49155e3c15ec0432cf9de1d4d38c44/server/config/config.go#L144

2. How would you like to improve it?

Add documentation for this configuration item.

[dveeden]

cc @rleungx @nolouch

[rleungx]

IMO, it's unnecessary to expose this config to the user. We don't expect the user to modify it because it could affect the online recovery when we use it to recover our cluster.

[dveeden]

Shouldn't we then document that the configuration item exists and that we strongly advise users not to change it?

[rleungx]

We also have other configs which are not exposed now. I'm not sure whether we should expose them with strong advice or not.