Tidy up etags.md

Author: stevepiercy

docs/deployment/caching/etags.md

@@ -1,9 +1,9 @@
 ---
 myst:
   html_meta:
-    "description": "ETags support for Plone caching"
-    "property=og:description": "ETags support for Plone caching"
-    "property=og:title": "ETags support for Plone"
+    "description": "ETags support for caching in Plone"
+    "property=og:description": "ETags support for caching in Plone"
+    "property=og:title": "ETags support for caching in Plone"
     "keywords": "Plone, deployment, automation, caching"
 ---
 
@@ -13,25 +13,26 @@ myst:
 
 ETags are used in to determine whether pages need to be re-calculated or can be served from cache.
 An ETag generated by `plone.app.caching` is a string of tokens separated by pipe characters that hold values like a user ID, the current skin name, or a counter indicating how many objects have been added to the site.
-This technique is used to quickly calculate the current ETag for the requested resource. 
-The browser sends a request with the ETag included in an `If-None-Match` header, and if the ETag is the same, Plone responds with a 304 NOT MODIFIED message, indicating that the browser should use its cached copy. 
-If the ETag is different, Plone renders the page and returns it as normal.
+This technique is used to quickly calculate the current ETag for the requested resource.
+The browser sends a request with the ETag included in an `If-None-Match` header.
+If the ETag is the same, then Plone responds with a `304 NOT MODIFIED` message, indicating that the browser should use its cached copy.
+If the ETag is different, then Plone renders the page and returns it as usual.
 
 Many caching operations use ETags. 
 The tokens to include are typically listed in an `etags` tuple in the operation's options.
 
 ## Default tokens
 
-The ETag names tokens supported by default are:
+The ETag token names supported by default are:
 
 | etag | description |
 | --- | --- |
-| userid | The current user's id .|
+| userid | The current user's ID.|
 | roles | A list of the current user's roles in the given context. |
 | language | The language(s) accepted by the browser, in the `ACCEPT_LANGUAGE` header. |
 | userLanguage | The current user's preferred language. |
 | lastModified | A timestamp indicating the last-modified date of the given context. |
-| catalogCounter | A counter that is incremented each time the catalog is updated. I.e. each time content in the site is changed. |
+| catalogCounter | A counter that is incremented each time the catalog is updated, such as when content in the site is changed. |
 | locked | Whether or not the given context is locked for editing. |
 | skin | The name of the current skin (theme). |
 | resourceRegistries | A timestamp indicating the last-modified timestamp for the Resource Registries. This is useful for avoiding requests for expired resources from cached pages. |
@@ -40,12 +41,12 @@ The ETag names tokens supported by default are:
 
 It is possible to provide additional tokens by registering an `IETagValue` adapter.
 
-This should be a named adapter on the published object (typically a view, file resource or Zope page template object) and request, with a unique name.
+This should be a named adapter on the published object (typically a view, file resource, or Zope page template object) and request, with a unique name.
 
 The name is used to look up the component. 
-Thus, you can also override one of the tokens above for a particular type of context or request (e.g. via a browser layer), by registering a more specific adapter with the same name.
+Thus you can override one of the tokens above for a particular type of context or request, including via a browser layer, by registering a more specific adapter with the same name.
 
-As an example, here is the `language` adapter:
+As an example, here is the `language` adapter.
 
 ```python
 from plone.app.caching.interfaces import IETagValue
@@ -68,7 +69,7 @@ class Language:
         return self.request.get('HTTP_ACCEPT_LANGUAGE', '')
 ```
 
-This is registered in `ZCML` like so:
+This is registered in `ZCML` as shown below.
 
 ```xml
 <adapter factory=".etags.Language" name="language" />