Links do not account for RTD multiple versions and ending is incorrect

### Describe the bug

One link would be https://ablog.readthedocs.io/manual/post-excerpts-and-images/ but in fact it is https://ablog.readthedocs.io/en/stable/manual/post-excerpts-and-images.html 

Support for RTD versions and tracking down the missing .html in the reference is important.