Update docs dependencies

Author: adfoster-r7

docs/Gemfile.lock

@@ -17,15 +17,15 @@ GEM
     byebug (11.1.3)
     coderay (1.1.3)
     colorator (1.1.0)
-    concurrent-ruby (1.3.4)
+    concurrent-ruby (1.3.5)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
     eventmachine (1.2.7)
-    ffi (1.17.0)
+    ffi (1.17.1)
     forwardable-extended (2.6.0)
     http_parser.rb (0.8.0)
-    i18n (1.14.6)
+    i18n (1.14.7)
       concurrent-ruby (~> 1.0)
     jekyll (4.3.4)
       addressable (~> 2.4)
@@ -76,7 +76,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
-    rexml (3.4.0)
+    rexml (3.4.1)
     rouge (4.5.1)
     safe_yaml (1.0.5)
     sassc (2.4.0)