Add jekyll-sitemap for /sitemap.xml generation

Gemfile

@@ -30,4 +30,5 @@ gem "wdm", "~> 0.1.1", :platforms => [:mingw, :x64_mingw, :mswin]
 
 gem "jekyll-github-metadata"
 gem "webrick", "~> 1.7"
-gem 'jekyll-redirect-from'
+gem 'jekyll-redirect-from'
+gem 'jekyll-sitemap'

Gemfile.lock

@@ -65,6 +65,8 @@ GEM
       sassc (> 2.0.1, < 3.0)
     jekyll-seo-tag (2.7.1)
       jekyll (>= 3.8, < 5.0)
+    jekyll-sitemap (1.4.0)
+      jekyll (>= 3.7, < 5.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
     kramdown (2.3.2)
@@ -121,6 +123,7 @@ DEPENDENCIES
   jekyll-feed (~> 0.12)
   jekyll-github-metadata
   jekyll-redirect-from
+  jekyll-sitemap
   minima (~> 2.5)
   tzinfo (~> 1.2)
   tzinfo-data

_config.yml

@@ -9,6 +9,7 @@ plugins:
   - jekyll-feed
   - "jekyll-github-metadata"
   - jekyll-redirect-from
+  - jekyll-sitemap
 include:
   - _pages
 exclude: