Link ELEMENT types to their element guide reference

### 📝 Description of the feature

As title says.

This was first mentioned in https://github.com/ansys/pymapdl/pull/3750#discussion_r2052538582.

### 💡 Steps for implementing the feature

_No response_

### 🔗 Useful links and references

_No response_

No files, tests, or entry points are named. Start by locating how the converter handles ELEMENT types and generates their Sphinx documentation, then review the linked discussion for the intended reference target. Done means generated ELEMENT types link to the corresponding element guide reference.

Written by the indexing model from the issue text.