Bump webrick from 1.8.1 to 1.8.2 in /docs (#602)

Author: dependabot[bot]

docs/Gemfile.lock

@@ -67,7 +67,7 @@ GEM
     terminal-table (3.0.2)
       unicode-display_width (>= 1.1.1, < 3)
     unicode-display_width (2.4.2)
-    webrick (1.8.1)
+    webrick (1.8.2)
 
 PLATFORMS
   ruby