Remove 10 minute cursorTimeout comment from GridFSFindOptions docs

[sanav33]

The cursor timeout value is now configurable on a per server basis: https://jira.mongodb.org/browse/SERVER-8188. Additionally, the spec did not mark the skip option in GridFSFindOptions as optional.

[ShaneHarvey]

Changes LGTM but I believe noCursorTimeout=True doesn't actually do anything at all on 4.4.8+ servers due to the session timeout behavior described in https://jira.mongodb.org/browse/DRIVERS-1602 and https://jira.mongodb.org/browse/SERVER-6036.

You might want to skip implementing the noCursorTimeout option altogether in Rust.

[alcaeus]

LGTM. As @ShaneHarvey commented, the session timeout (which comes into effect for operations outside a session due to the drivers starting an implicit session) overrides the noCursorTimeout option, again creating an implicit timeout for cursors.

[kmahar]

Thanks for the extra context @ShaneHarvey and @alcaeus. I agree we could probably skip this option then @sanav33, we've got very few users on MongoDB versions < 5.0