Merge pull request #1458 from gruntwork-io/dependabot/bundler/docs/rexml-3.3.9

Bump rexml from 3.3.3 to 3.3.9 in /docs

Author: eric-Grunt

docs/Gemfile.lock

@@ -231,8 +231,7 @@ GEM
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     ref (2.0.0)
-    rexml (3.3.3)
-      strscan
+    rexml (3.3.9)
     rouge (3.26.0)
     rubyzip (2.3.0)
     safe_yaml (1.0.5)
@@ -246,7 +245,6 @@ GEM
       faraday (> 0.8, < 2.0)
     simpleidn (0.1.1)
       unf (~> 0.1.4)
-    strscan (3.1.0)
     terminal-table (1.8.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     therubyracer (0.12.3)