[Doc] The user rights management doc is out of data

[frank-zsy]

Describe the bug

In production env, we really need a user access management for our databases.

But in the User rights management doc, the functions are out of date right now and can not be used to setup user access rights correctly like:

• modSpecifiedAccessLevel function does not exist anymore, the name of the function should be modRoleAccessLevel now, so there will be an error about unregistered standalone function if we call modSpecifiedAccessLevel in the Cypher.

I think we should keep the document identical with the code at our best to make sure users can setup the database properly by themselves.

[frank-zsy]

Also, we should give some examples about how to use the functions since users may not understand how to properly set a Map param to functions like CALL dbms.security.modSpecifiedAccessLevel(role::STRING,access_level::MAP).

[knightast]

A lot of efforts should be made to enhance doc, thanks for detailed suggestion.

Currently, all interface are tested in UT, you can also find the examples in UT (which should be put in doc).

[frank-zsy]

I think I can help with the update of this doc and sync the function from UT to doc.