[doc] Update gems

docs/Gemfile.lock

@@ -16,7 +16,7 @@ GEM
     colorator (1.1.0)
     commonmarker (0.17.13)
       ruby-enum (~> 0.5)
-    concurrent-ruby (1.1.5)
+    concurrent-ruby (1.1.6)
     dnsruby (1.61.3)
       addressable (~> 2.5)
     em-websocket (0.5.1)
@@ -28,10 +28,10 @@ GEM
     execjs (2.7.0)
     faraday (1.0.0)
       multipart-post (>= 1.2, < 3)
-    ffi (1.12.1)
+    ffi (1.12.2)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
-    github-pages (203)
+    github-pages (204)
       github-pages-health-check (= 1.16.1)
       jekyll (= 3.8.5)
       jekyll-avatar (= 0.7.0)
@@ -40,7 +40,7 @@ GEM
       jekyll-default-layout (= 0.1.4)
       jekyll-feed (= 0.13.0)
       jekyll-gist (= 1.5.0)
-      jekyll-github-metadata (= 2.12.1)
+      jekyll-github-metadata (= 2.13.0)
       jekyll-mentions (= 1.5.1)
       jekyll-optional-front-matter (= 0.3.2)
       jekyll-paginate (= 1.1.0)
@@ -117,8 +117,8 @@ GEM
       jekyll (>= 3.7, < 5.0)
     jekyll-gist (1.5.0)
       octokit (~> 4.2)
-    jekyll-github-metadata (2.12.1)
-      jekyll (~> 3.4)
+    jekyll-github-metadata (2.13.0)
+      jekyll (>= 3.4, < 5.0)
       octokit (~> 4.0, != 4.4.0)
     jekyll-mentions (1.5.1)
       html-pipeline (~> 2.3)
@@ -204,9 +204,9 @@ GEM
       jekyll-seo-tag (~> 2.1)
     minitest (5.14.0)
     multipart-post (2.1.1)
-    nokogiri (1.10.7)
+    nokogiri (1.10.8)
       mini_portile2 (~> 2.4.0)
-    octokit (4.15.0)
+    octokit (4.16.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.16.2)
@@ -218,7 +218,7 @@ GEM
     rouge (3.13.0)
     ruby-enum (0.7.2)
       i18n
-    rubyzip (2.0.0)
+    rubyzip (2.2.0)
     safe_yaml (1.0.5)
     sass (3.7.4)
       sass-listen (~> 4.0.0)