[jsscripting] Improve docs with Actions (#11624)

[jsscripting] Improve docs with Actions (#11624)

Updated the documentation with:
* Core Actions
* Cloud Notification Actions
* Persistence Extensions
* Ephemeris Actions
* Types and Units

Instead of the single "imports", the default scope
(openhab-core/DefaultScriptScopeProvider.java) is used.
It's imported as `openhab`, services are under `openhab.service`.

As the helper library is on the way (openhab/openhab-js):
* Added note about console.log and logging in general.
* Added note that the lib is on the way.

Signed-off-by: Florian Hotze <florianh_dev@icloud.com>