Clean up of caching/index.md

- We cache content in Plone, not Plone itself.
- Headings for overview or introduction are unnecessary, and leaving a heading without content looks weird. Instead just smoosh an introduction under the page title.
- Shorten introduction of caching.
- Add Glossary term of CDN.
- Add link to plone.app.caching repo.
- Grammar fixes.

Author: stevepiercy

docs/deployment/caching/index.md

@@ -1,32 +1,31 @@
 ---
 myst:
   html_meta:
-    "description": "Caching Plone"
-    "property=og:description": "Caching Plone"
-    "property=og:title": "Caching Plone"
+    "description": "Caching content in Plone"
+    "property=og:description": "Caching content in Plone"
+    "property=og:title": "Caching content in Plone"
     "keywords": "Plone, deployment, automation, caching"
 ---
 
 (caching-label)=
 
 # Caching
 
-## Overview
+HTTP caching is a technique used to speed up the delivery of web content by storing previously requested resources, such as images, scripts, and stylesheets, in a cache.
 
-HTTP caching is a technique used to speed up the delivery of web content by storing previously requested resources (such as images, scripts, and stylesheets) in a cache. 
-When a user requests a resource, the cache can serve the resource directly from its storage, rather than having to fetch it from the original source.
+A web accelerator, such as {term}`Varnish`, may be used to implement HTTP caching.
+The usual set up will place the web accelerator between Plone and the Internet.
+When a request is made to the site, the web accelerator will intercept the request.
+It then checks to see if it has a cached copy of the requested resource.
+If a cached copy is found, the accelerator will serve the cached copy directly to the client, else it will make a request to the backend Plone server and then store a copy on the content in its local cache.
 
-It is possible to use a web accelerator, like {term}`Varnish` to implement HTTP caching in your own premises. 
-The usual setup will have the web accelerator installed between Plone and the Internet, and when a request is made to the site the web accelerator will intercept the request and check to see if it has a cached copy of the requested resource. 
-If a cached copy is found, the accelerator will serve the cached copy directly to the client, otherwise it will make a request to the backend Plone server and then store a copy on the content in its local cache.
-
-HTTP caching and the speed of delivering web content can be improved using a Content Delivery Network (CDN).
-A CDN is a network of servers located in various geographic regions that work together to deliver web content to users quickly and efficiently. 
+HTTP caching and the speed of delivering web content can be improved using a {term}`Content Delivery Network` (CDN).
+A CDN is a network of servers located in various geographic regions that work together to deliver web content to users quickly and efficiently.
 When a user requests a resource from a website that uses a CDN, the request is directed to the closest server in the CDN, rather than having to travel all the way to the website's origin server.
 
-## Plone support
+## Cache support in Plone
 
-Plone ships with a powerful and extensible `HTTP` and `In-Memory` cache support, implemented by the package `plone.app.caching`.
+Plone ships with powerful and extensible `HTTP` and `In-Memory` cache support, implemented by the package [`plone.app.caching`](https://github.com/plone/plone.app.caching/).
 
 
 ```{toctree}

docs/glossary.md

@@ -638,4 +638,8 @@ acquisition
 
 Varnish
     [Varnish](https://varnish-cache.org) is a popular open source web accelerator that is used to implement HTTP caching.
+
+Content Delivery Network
+CDN
+    A Content Delivery Network (CDN) is a network of servers located in various geographic regions that work together to deliver web content to users quickly and efficiently.
 ```