jekyll: fix sitemap lastmod

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.dockerignore

@@ -1,5 +1,4 @@
 .DS_Store
-.git
 .github
 .gitignore
 .idea

Gemfile

@@ -5,6 +5,7 @@ gem 'wdm', '>= 0.1.0' if Gem.win_platform?
 
 gem 'jekyll', '4.2.2'
 group :jekyll_plugins do
+  gem 'jekyll-last-modified-at'
   gem 'jekyll-redirect-from'
   gem 'jekyll-relative-links'
   gem 'jekyll-sitemap'

Gemfile.lock

@@ -45,6 +45,9 @@ GEM
       rouge (~> 3.0)
       safe_yaml (~> 1.0)
       terminal-table (~> 2.0)
+    jekyll-last-modified-at (1.3.0)
+      jekyll (>= 3.7, < 5.0)
+      posix-spawn (~> 0.3.9)
     jekyll-redirect-from (0.16.0)
       jekyll (>= 3.3, < 5.0)
     jekyll-relative-links (0.6.1)
@@ -88,6 +91,7 @@ GEM
     parallel (1.22.1)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
+    posix-spawn (0.3.15)
     public_suffix (4.0.7)
     racc (1.6.0)
     rainbow (3.1.1)
@@ -118,6 +122,7 @@ DEPENDENCIES
   front_matter_parser (= 1.0.1)
   html-proofer (= 3.19.4)
   jekyll (= 4.2.2)
+  jekyll-last-modified-at
   jekyll-redirect-from
   jekyll-relative-links
   jekyll-sitemap

_config.yml

@@ -102,6 +102,24 @@ defaults:
       toc_min: 2
       toc_max: 4
 
+  # Exclude from sitemap
+  - scope:
+      path: "assets/**"
+    values:
+      sitemap: false
+  - scope:
+      path: "**/nav.html"
+    values:
+      sitemap: false
+  - scope:
+      path: "google*.html"
+    values:
+      sitemap: false
+  - scope:
+      path: "**/*.pdf"
+    values:
+      sitemap: false
+
   # Set the correct edit-URL for some local and remote resources. We usually don't create a direct
   # edit link for these, and instead point to the directory that contains the file.
   - scope: