Bump jekyll-feed from 0.15.1 to 0.16.0 in /docs

Bumps [jekyll-feed](https://github.com/jekyll/jekyll-feed) from 0.15.1 to 0.16.0.
- [Release notes](https://github.com/jekyll/jekyll-feed/releases)
- [Changelog](https://github.com/jekyll/jekyll-feed/blob/master/History.markdown)
- [Commits](jekyll/jekyll-feed@v0.15.1...v0.16.0)

---
updated-dependencies:
- dependency-name: jekyll-feed
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

docs/Gemfile.lock

@@ -4,14 +4,14 @@ GEM
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
-    concurrent-ruby (1.1.7)
-    em-websocket (0.5.2)
+    concurrent-ruby (1.1.10)
+    em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
-      http_parser.rb (~> 0.6.0)
+      http_parser.rb (~> 0)
     eventmachine (1.2.7)
-    ffi (1.13.1)
+    ffi (1.15.5)
     forwardable-extended (2.6.0)
-    http_parser.rb (0.6.0)
+    http_parser.rb (0.8.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
     jekyll (3.9.0)
@@ -29,7 +29,7 @@ GEM
       safe_yaml (~> 1.0)
     jekyll-archives (2.2.1)
       jekyll (>= 3.6, < 5.0)
-    jekyll-feed (0.15.1)
+    jekyll-feed (0.16.0)
       jekyll (>= 3.7, < 5.0)
     jekyll-paginate (1.1.0)
     jekyll-sass-converter (1.5.2)
@@ -43,10 +43,10 @@ GEM
       jekyll-seo-tag (~> 2.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (2.3.0)
+    kramdown (2.4.0)
       rexml
     liquid (4.0.3)
-    listen (3.2.1)
+    listen (3.7.1)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
@@ -56,12 +56,12 @@ GEM
       jekyll-seo-tag (~> 2.1)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (4.0.6)
-    rb-fsevent (0.10.4)
+    public_suffix (4.0.7)
+    rb-fsevent (0.11.1)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.4)
-    rouge (3.23.0)
+    rexml (3.2.5)
+    rouge (3.28.0)
     safe_yaml (1.0.5)
     sass (3.7.4)
       sass-listen (~> 4.0.0)