Documentation Signal quick start link to missing anchor

[IshaGeurtsen]

in Documentation/Signals in the introduction section there is a link to the #quick-start anchor. but the actual named anchor is #signals-quick-start as seen by doctoc's summary

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<details>
<summary>Details</summary>

- [Introduction](#introduction)
  - [Signals Quick Start](#signals-quick-start)
  - truncated
</details>
<!-- END doctoc generated TOC please keep comment here to allow auto update -->

* Introduction
    * <a href="#quick-start">Signals Quick Start</a>
    * truncated