Bump kramdown from 2.3.0 to 2.3.1 in /docs

Bumps [kramdown](https://github.com/gettalong/kramdown) from 2.3.0 to 2.3.1.
- [Release notes](https://github.com/gettalong/kramdown/releases)
- [Changelog](https://github.com/gettalong/kramdown/blob/master/doc/news.page)
- [Commits](https://github.com/gettalong/kramdown/commits)

---
updated-dependencies:
- dependency-name: kramdown
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/Gemfile.lock

@@ -31,55 +31,41 @@ GEM
     ffi (1.13.1)
     forwardable-extended (2.6.0)
     gemoji (3.0.1)
-    github-pages (207)
-      github-pages-health-check (= 1.16.1)
+    github-pages (217)
+      github-pages-health-check (= 1.17.2)
       jekyll (= 3.9.0)
       jekyll-avatar (= 0.7.0)
       jekyll-coffeescript (= 1.1.1)
       jekyll-commonmark-ghpages (= 0.1.6)
       jekyll-default-layout (= 0.1.4)
-      jekyll-feed (= 0.13.0)
+      jekyll-feed (= 0.15.1)
       jekyll-gist (= 1.5.0)
       jekyll-github-metadata (= 2.13.0)
-      jekyll-mentions (= 1.5.1)
+      jekyll-mentions (= 1.6.0)
       jekyll-optional-front-matter (= 0.3.2)
       jekyll-paginate (= 1.1.0)
       jekyll-readme-index (= 0.3.0)
-      jekyll-redirect-from (= 0.15.0)
+      jekyll-redirect-from (= 0.16.0)
       jekyll-relative-links (= 0.6.1)
-      jekyll-remote-theme (= 0.4.1)
+      jekyll-remote-theme (= 0.4.3)
       jekyll-sass-converter (= 1.5.2)
-      jekyll-seo-tag (= 2.6.1)
+      jekyll-seo-tag (= 2.7.1)
       jekyll-sitemap (= 1.4.0)
-      jekyll-swiss (= 1.0.0)
-      jekyll-theme-architect (= 0.1.1)
-      jekyll-theme-cayman (= 0.1.1)
-      jekyll-theme-dinky (= 0.1.1)
-      jekyll-theme-hacker (= 0.1.1)
-      jekyll-theme-leap-day (= 0.1.1)
-      jekyll-theme-merlot (= 0.1.1)
-      jekyll-theme-midnight (= 0.1.1)
-      jekyll-theme-minimal (= 0.1.1)
-      jekyll-theme-modernist (= 0.1.1)
-      jekyll-theme-primer (= 0.5.4)
-      jekyll-theme-slate (= 0.1.1)
-      jekyll-theme-tactile (= 0.1.1)
-      jekyll-theme-time-machine (= 0.1.1)
       jekyll-titles-from-headings (= 0.5.3)
-      jemoji (= 0.11.1)
-      kramdown (= 2.3.0)
+      jemoji (= 0.12.0)
+      kramdown (= 2.3.1)
       kramdown-parser-gfm (= 1.1.0)
       liquid (= 4.0.3)
       mercenary (~> 0.3)
       minima (= 2.5.1)
       nokogiri (>= 1.10.4, < 2.0)
-      rouge (= 3.19.0)
+      rouge (= 3.26.0)
       terminal-table (~> 1.4)
-    github-pages-health-check (1.16.1)
+    github-pages-health-check (1.17.2)
       addressable (~> 2.3)
       dnsruby (~> 1.60)
       octokit (~> 4.0)
-      public_suffix (~> 3.0)
+      public_suffix (>= 2.0.2, < 5.0)
       typhoeus (~> 1.3)
     html-pipeline (2.14.3)
       activesupport (>= 2)
@@ -114,85 +100,45 @@ GEM
       rouge (>= 2.0, < 4.0)
     jekyll-default-layout (0.1.4)
       jekyll (~> 3.0)
-    jekyll-feed (0.13.0)
+    jekyll-feed (0.15.1)
       jekyll (>= 3.7, < 5.0)
     jekyll-gist (1.5.0)
       octokit (~> 4.2)
     jekyll-github-metadata (2.13.0)
       jekyll (>= 3.4, < 5.0)
       octokit (~> 4.0, != 4.4.0)
-    jekyll-mentions (1.5.1)
+    jekyll-mentions (1.6.0)
       html-pipeline (~> 2.3)
       jekyll (>= 3.7, < 5.0)
     jekyll-optional-front-matter (0.3.2)
       jekyll (>= 3.0, < 5.0)
     jekyll-paginate (1.1.0)
     jekyll-readme-index (0.3.0)
       jekyll (>= 3.0, < 5.0)
-    jekyll-redirect-from (0.15.0)
+    jekyll-redirect-from (0.16.0)
       jekyll (>= 3.3, < 5.0)
     jekyll-relative-links (0.6.1)
       jekyll (>= 3.3, < 5.0)
-    jekyll-remote-theme (0.4.1)
+    jekyll-remote-theme (0.4.3)
       addressable (~> 2.0)
       jekyll (>= 3.5, < 5.0)
-      rubyzip (>= 1.3.0)
+      jekyll-sass-converter (>= 1.0, <= 3.0.0, != 2.0.0)
+      rubyzip (>= 1.3.0, < 3.0)
     jekyll-sass-converter (1.5.2)
       sass (~> 3.4)
-    jekyll-seo-tag (2.6.1)
-      jekyll (>= 3.3, < 5.0)
+    jekyll-seo-tag (2.7.1)
+      jekyll (>= 3.8, < 5.0)
     jekyll-sitemap (1.4.0)
       jekyll (>= 3.7, < 5.0)
-    jekyll-swiss (1.0.0)
-    jekyll-theme-architect (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-cayman (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-dinky (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-hacker (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-leap-day (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-merlot (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-midnight (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-minimal (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-modernist (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-primer (0.5.4)
-      jekyll (> 3.5, < 5.0)
-      jekyll-github-metadata (~> 2.9)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-slate (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-tactile (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
-    jekyll-theme-time-machine (0.1.1)
-      jekyll (~> 3.5)
-      jekyll-seo-tag (~> 2.0)
     jekyll-titles-from-headings (0.5.3)
       jekyll (>= 3.3, < 5.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    jemoji (0.11.1)
+    jemoji (0.12.0)
       gemoji (~> 3.0)
       html-pipeline (~> 2.2)
       jekyll (>= 3.0, < 5.0)
-    kramdown (2.3.0)
+    kramdown (2.3.1)
       rexml
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
@@ -222,7 +168,7 @@ GEM
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rexml (3.2.5)
-    rouge (3.19.0)
+    rouge (3.26.0)
     ruby-enum (0.8.0)
       i18n
     rubyzip (2.3.2)