incorrect DocBlock for set-screen-option filter

[pbiron]

This is a follow-up to #26186.

The first param in the DocBLock in the patch committed in r27379 is incorrect, in a couple of ways:

1. the param type should be bool
2. the param name should be something like $keep (see below)
3. the param description should be something like Whether to keep or skip saving the screen option value. Default false.

The fact that the incorrect name $value is also the name of another one of the params causes phpdoc-parser to skip outputting the param altogether in the Code Reference: ​https://developer.wordpress.org/reference/hooks/set-screen-option/ (caused me a few minutes of grief wondering why my screen options weren't being saved).

Related: #42505

[burhandodhy]

As par pbiron recommendation

[SergeyBiryukov]

In 44667:

Docs: Correct type and description for the first parameter of set-screen-option filter.

Props pbiron, burhandodhy.
Fixes #44850.