Remove erroneuous comma

Author: umerhasan17

docs/source/migration_guides.md

@@ -7,7 +7,7 @@ widgets.
 Migrating from 6.0 to 7.0
 -------------------------
 
-For example, migrations, see these PRs:
+For example migrations, see these PRs:
  - [ipyleaflet](https://github.com/ellisonbg/ipyleaflet/pull/66)
  - [jupyter-gmaps](https://github.com/pbugnion/gmaps/pull/166)
  - bqplot: [PR #458](https://github.com/bloomberg/bqplot/pull/458), [PR #497](https://github.com/bloomberg/bqplot/pull/497) and [PR #501](https://github.com/bloomberg/bqplot/pull/501)