Revert "eolian: disallow missing docs for stable API where necessary"
I'm afraid but this breaks the mono bindings too close to a release.
This also fixes the missing docs errors by adding a lot of inconsistent
placeholder text ("No description supplied.", "TBD") which will make
finding them later on more complicated.
I was the one that asked for this feature but it is not critical at this
point, so I suggest we explore some refinements (like T8291) before landing
this patch in its current state.
This reverts commit 2946cb3c325f27d77354ac1b83b614e3a1d9e1d5.