Unnecessary anchor tags in markup

The markdown for each reference page creates a few anchor tags:
```asciidoc
[#overview]
[#howtouse]
[#see_also]
```
However, it's not clear to me that these are needed. The reason is that anchors are automatically generated for each heading in the page. This means that https://www.arduino.cc/reference/en/language/functions/digital-io/digitalread/#_example_code works just as well as https://www.arduino.cc/reference/en/language/functions/digital-io/digitalread/#howtouse. For this reason, it seems like the manually added anchors only clutter up the reference source, making the content less friendly to casual contributors. Perhaps there is some purpose to these I'm not aware of? If not, I propose that I remove them, and update any links in the reference content that use them.

The issue identifies reference-page source markup and links using #overview, #howtouse, and #see_also; begin by locating those anchors and their incoming links. Confirm whether generated heading anchors cover the references, then remove redundant anchors and update affected links only if that audit confirms they are unnecessary.

Written by the indexing model from the issue text.