[DOCS] broken link

[Deufel]

Issue Type

• [ X] Existing documentation (e.g. typos, errors, outdated information)
• [ ] Suggest new documentation that is currently missing

Current Behavior or Documentation Gaps
For existing documentation:
The (Defining new ft components)Link on (https://fastht.ml/docs/explains/explaining_xt_components.html) is missing the html in the mark-up

Suggested Improvement or New Documentation Content
fix link

Relevant Links
If this issue relates to existing features, APIs, or other projects, please provide relevant links to help clarify the issue or suggested documentation. This [page](https://fastht.ml/docs/explains/explaining_xt_components.html) has a broken link it is missing the "html"

Confirmation
Please confirm the following:

• [ x] I have checked the existing issues and pull requests to ensure this documentation issue hasn't been reported before.
• [ x] I have read the project's documentation and am confident this issue or suggestion is valid.