Bump redcarpet from 3.5.1 to 3.6.0 in /docs/_spec

Bumps [redcarpet](https://github.com/vmg/redcarpet) from 3.5.1 to 3.6.0.
- [Release notes](https://github.com/vmg/redcarpet/releases)
- [Changelog](https://github.com/vmg/redcarpet/blob/master/CHANGELOG.md)
- [Commits](vmg/redcarpet@v3.5.1...v3.6.0)

---
updated-dependencies:
- dependency-name: redcarpet
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
[Cherry-picked 02153d6]

Author: dependabot[bot]

docs/_spec/Gemfile

@@ -5,4 +5,4 @@ gem "jekyll", "3.6.3"
 gem "webrick"
 gem "rouge"
 # gem 's3_website'
-gem "redcarpet", "3.5.1"
+gem "redcarpet", "3.6.0"

docs/_spec/Gemfile.lock

@@ -33,7 +33,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    redcarpet (3.5.1)
+    redcarpet (3.6.0)
     rouge (2.2.1)
     safe_yaml (1.0.5)
     sass (3.7.4)
@@ -49,7 +49,7 @@ PLATFORMS
 
 DEPENDENCIES
   jekyll (= 3.6.3)
-  redcarpet (= 3.5.1)
+  redcarpet (= 3.6.0)
   rouge
   webrick