Bump jekyll-watch from 2.0.0 to 2.1.0 in /docs

Bumps [jekyll-watch](https://github.com/jekyll/jekyll-watch) from 2.0.0 to 2.1.0.
- [Release notes](https://github.com/jekyll/jekyll-watch/releases)
- [Changelog](https://github.com/jekyll/jekyll-watch/blob/master/History.markdown)
- [Commits](https://github.com/jekyll/jekyll-watch/compare/v2.0.0...v2.1.0

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

docs/Gemfile.lock

@@ -195,7 +195,7 @@ GEM
       jekyll-seo-tag (~> 2.0)
     jekyll-titles-from-headings (0.5.1)
       jekyll (~> 3.3)
-    jekyll-watch (2.0.0)
+    jekyll-watch (2.1.0)
       listen (~> 3.0)
     jemoji (0.10.1)
       gemoji (~> 3.0)