docs, remove unneeded `\` and remove trailing whitespace. [ci skip]
Don't accept parameters as argument for redirect to [via @homakov]

Closes #16170
nodoc enum hooks [ci skip]
docs, `select` and friends with `multiple=true` include a blank string.

[Jonas Baumann & Yves Senn]

The submitted params from a select with `multiple: true` look as follows:

```
{post: {category: [""]}}

{post: {category: ["", "Category 1", "Category 2"]}}
```

This is a follow up to #1552.
Fix that render layout should also be picked up by the template dependency tracker, but only half-ways. You can add that layout option on the same render call, and both templates should be added to the dependency tree. But thats going to require a more serious rework of the tracker. Please do help fix this part of it too. For now, render layout needs to be on its own line.