docs/glossary: Add Content Delivery Network entry (#22507)

* docs/glossary: Add Content Delivery Network entry

Also updated glossary.md and doc-links.yaml with links to the new entry.

* Update docs/docs/glossary/content-delivery-network.md

Add a necessary comma after 'Without a content delivery network,'

Co-Authored-By: Aisha Blake <aisha@gatsbyjs.com>

* Edit relative links

Co-authored-by: Aisha Blake <aisha@gatsbyjs.com>

yarn.lock

@@ -7960,12 +7960,12 @@ lodash.uniq@^4.5.0:
   resolved "https://registry.yarnpkg.com/lodash.uniq/-/lodash.uniq-4.5.0.tgz#d0225373aeb652adc1bc82e4945339a842754773"
   integrity sha1-0CJTc662Uq3BvILklFM5qEJ1R3M=
 
-lodash@^4.11.1, lodash@^4.13.1, lodash@^4.15.0, lodash@^4.17.11, lodash@^4.17.12, lodash@^4.17.13, lodash@^4.17.14, lodash@^4.17.4, lodash@^4.17.5, lodash@^4.3.0:
+lodash@^4.11.1, lodash@^4.13.1, lodash@^4.15.0, lodash@^4.17.11, lodash@^4.17.12, lodash@^4.17.13, lodash@^4.17.4, lodash@^4.17.5, lodash@^4.3.0:
   version "4.17.14"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.14.tgz#9ce487ae66c96254fe20b599f21b6816028078ba"
   integrity sha512-mmKYbW3GLuJeX+iGP+Y7Gp1AiGHGbXHCOh/jZmrawMmsE7MS4znI3RL2FsjbqOyMayHInjOeykW7PEajUk1/xw==
 
-lodash@^4.17.15:
+lodash@^4.17.14, lodash@^4.17.15:
   version "4.17.15"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.15.tgz#b447f6670a0455bbfeedd11392eff330ea097548"
   integrity sha512-8xOcRHvCjnocdS5cpwXQXVzmmh5e5+saE2QGoeQmbKmRS6J3VQppPOIt0MnmE+4xlZoumy0GPG0D0MVIQbNA1A==