gem update

Gemfile.lock

+PATH
+  remote: .
+  specs:
+    just-the-docs (0.3.0)
+      jekyll (>= 3.8.5)
+      jekyll-seo-tag (~> 2.0)
+      rake (>= 12.3.1, < 13.1.0)
+
 GEM
   remote: https://rubygems.org/
   specs:
-    bundler
-    addressable (2.5.0)
-      public_suffix (~> 2.0, >= 2.0.2)
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
     colorator (1.1.0)
-    ffi (1.9.17)
+    concurrent-ruby (1.1.6)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.7)
+    ffi (1.13.1)
     forwardable-extended (2.6.0)
-    jekyll (3.4.0)
+    http_parser.rb (0.6.0)
+    i18n (1.8.3)
+      concurrent-ruby (~> 1.0)
+    jekyll (4.1.1)
       addressable (~> 2.4)
       colorator (~> 1.0)
-      jekyll-sass-converter (~> 1.0)
-      jekyll-watch (~> 1.1)
-      kramdown (~> 1.3)
-      liquid (~> 3.0)
-      mercenary (~> 0.3.3)
+      em-websocket (~> 0.5)
+      i18n (~> 1.0)
+      jekyll-sass-converter (~> 2.0)
+      jekyll-watch (~> 2.0)
+      kramdown (~> 2.1)
+      kramdown-parser-gfm (~> 1.0)
+      liquid (~> 4.0)
+      mercenary (~> 0.4.0)
       pathutil (~> 0.9)
-      rouge (~> 1.7)
+      rouge (~> 3.0)
       safe_yaml (~> 1.0)
-    jekyll-sass-converter (1.5.0)
-      sass (~> 3.4)
-    jekyll-watch (1.5.0)
-      listen (~> 3.0, < 3.1)
-    kramdown (1.13.2)
-    liquid (3.0.6)
-    listen (3.0.8)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
-    mercenary (0.3.6)
-    pathutil (0.14.0)
+      terminal-table (~> 1.8)
+    jekyll-sass-converter (2.1.0)
+      sassc (> 2.0.1, < 3.0)
+    jekyll-seo-tag (2.6.1)
+      jekyll (>= 3.3, < 5.0)
+    jekyll-watch (2.2.1)
+      listen (~> 3.0)
+    kramdown (2.3.0)
+      rexml
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    liquid (4.0.3)
+    listen (3.2.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.4.0)
+    pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (2.0.5)
-    rb-fsevent (0.9.8)
-    rb-inotify (0.9.8)
-      ffi (>= 0.5.0)
-    rouge (1.11.1)
-    safe_yaml (1.0.4)
-    sass (3.4.23)
+    public_suffix (4.0.5)
+    rake (13.0.1)
+    rb-fsevent (0.10.4)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rexml (3.2.4)
+    rouge (3.20.0)
+    safe_yaml (1.0.5)
+    sassc (2.4.0)
+      ffi (~> 1.9)
+    terminal-table (1.8.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    unicode-display_width (1.7.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  jekyll (= 3.4.0)
-  tzinfo-data
-
-RUBY VERSION
-   ruby 2.3.1p112
+  bundler (~> 2.1.4)
+  just-the-docs!
 
 BUNDLED WITH
-   1.13.6
+   2.1.4