[doc] nested markup is invalid in rst (#9898)
Apparently nested markup in RST is invalid: https://docutils.sourceforge.io/FAQ.html#is-nested-inline-markup-possible
So currently this line doesn't get rendered properly, leaving inner markdown unrendered, resulting in:
```
https://docutils.sourceforge.io/FAQ.html#is-nested-inline-markup-possible
```
This PR removes the bold which fixes the link.
