Add a simple tag/keyword for each node, allowing searching related functions by different names

[EduardoLemos567]

Feature/enhancement description:
A tag/keyword system on each node to allow searching related functions name from shader or even other programs.
For example, i was searching 'seamless' but there's a node called 'Make Tileable', if there was a keyword on it, it would be found by the keyword. Also for people coming from different tools, searching a node they are familiar and founding the related nodes for that function/action would cause a more seamless transition.

Also while we are at it, if you would implement a simple F1 help popup with some images and infos, for example, i'm not sure what each socket color means. Just a simple infographic/cheatsheet with main functions, symbology, would be great for new comers. Show it at first time and inform that we can press F1 to open it again.

Thank you for the tool

[RodZill4]

The tag system exists already (try to search "alveolus", for example). You can define your own tags for a node (just right click it in the library panel and select "define aliases").