Update docs/Gemfile.lock for nokogiri cve (#4116)

Summary:
Per GitHub warning
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4116

Differential Revision: D8812291

Pulled By: gfosco

fbshipit-source-id: 3c55adc4ac737e4be077ddf29322c8961018d67c

docs/Gemfile.lock

@@ -11,14 +11,15 @@ GEM
     coffee-script (2.4.1)
       coffee-script-source
       execjs
-    coffee-script-source (1.10.0)
+    coffee-script-source (1.12.2)
     colorator (1.1.0)
-    ethon (0.9.1)
+    concurrent-ruby (1.0.5)
+    ethon (0.11.0)
       ffi (>= 1.3.0)
     execjs (2.7.0)
-    faraday (0.9.2)
+    faraday (0.15.2)
       multipart-post (>= 1.2, < 3)
-    ffi (1.9.14)
+    ffi (1.9.25)
     forwardable-extended (2.6.0)
     gemoji (2.1.0)
     github-pages (104)
@@ -53,7 +54,7 @@ GEM
       typhoeus (~> 0.7)
     html-pipeline (2.4.2)
       activesupport (>= 2)
-      nokogiri (>= 1.4)
+      nokogiri (~> 1.8.2)
     i18n (0.7.0)
     jekyll (3.3.0)
       addressable (~> 2.4)
@@ -110,7 +111,7 @@ GEM
     minitest (5.9.1)
     multipart-post (2.0.0)
     net-dns (0.8.0)
-    nokogiri (1.8.1)
+    nokogiri (~> 1.8.2)
       mini_portile2 (~> 2.3.0)
     octokit (4.4.1)
       sawyer (~> 0.7.0, >= 0.5.3)