More detailed documentation regarding "https://github.com/phpredis/phpredis#php-session-handler" #1431

Expected behaviour

Documentation should include how weighting works, and what happens when one redis server goes down and then back up.
i.e. if there are 3 servers and one redis goes down will the sessions be lost? what happens when that redis server goes back up? are session connections reads/writes sent to one serves according to weights or all servers?
Also, the example shows "read_timeout" which is not in the documentation.

Actual behaviour

Include documentation regarding how weighting works, and what happens when one redis server goes down and then back up.
Include explanation regarding "read_timeout" or if wrong option, delete it altogether.

I'm seeing this behaviour on

https://github.com/phpredis/phpredis#php-session-handler

Steps to reproduce, backtrace or example script

I've checked

• [O] There is no similar issue from other users
• [O] Issue isn't fixed in develop branch