Convert old-style EDoc comments to Markdown via ELP

Summary:
This is an automatic conversion of old-style EDoc comments to Markdown, using ELP:

```
elp -- lint --diagnostic-filter W0038  --module edb --apply-fix --in-place --one-shot
```

Eventual, manual tweaks will follow.

Reviewed By: TheGeorge

Differential Revision: D71890596

fbshipit-source-id: b1fd4f7cdd2ca49ef7b7eb8d14b927af4a327ddf

Author: robertoaloi