docs: Switch to StackPath's URL.

While the old one will keep working, better switch to the new one.

_config.yml

@@ -67,9 +67,9 @@ download:
 
 cdn:
   # See https://www.srihash.org for info on how to generate the hashes
-  css:              "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"
+  css:              "https://stackpath.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"
   css_hash:         "sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm"
-  js:               "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
+  js:               "https://stackpath.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js"
   js_hash:          "sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl"
   jquery:           "https://code.jquery.com/jquery-3.3.1.slim.min.js"
   jquery_hash:      "sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo"

docs/4.0/getting-started/introduction.md

@@ -13,7 +13,7 @@ toc: true
 
 ## Quick start
 
-Looking to quickly add Bootstrap to your project? Use BootstrapCDN, provided for free by the folks at MaxCDN. Using a package manager or need to download the source files? [Head to the downloads page.]({{ site.baseurl }}/docs/{{ site.docs_version }}/getting-started/download/)
+Looking to quickly add Bootstrap to your project? Use BootstrapCDN, provided for free by the folks at StackPath. Using a package manager or need to download the source files? [Head to the downloads page.]({{ site.baseurl }}/docs/{{ site.docs_version }}/getting-started/download/)
 
 ### CSS