Add class comment for Signal/BaseSignal

**Describe the bug**

I'm confused about how the signal stuff works, would be great if the class itself had header comments.

**Annoyment level**

> How annoyed are you in a scale of 1-3 because this shitty code doesn't work properly

* [x] 1 - No rush from my side
* [ ] 2 - It is inconvenient, but I can circumvent the issue for now
* [ ] 3 - FUUUU
* [ ] 4

**Payment**

sponsor.

Locate the Signal and BaseSignal classes and read their surrounding code to understand what the class comments should explain. Add header comments to both classes describing how the signal code works, then verify that the comments are present and accurate.

Written by the indexing model from the issue text.