Clarify 0.117 breaking changes for templates (#15361)

source/_posts/2020-10-28-release-117.markdown

@@ -238,7 +238,7 @@ No configuration changes are necessary, to keep existing configs working, the ke
 </details>
 
 <details>
-  <summary><b>Templates</b></summary>
+  <summary><b>Templates - native types</b></summary>
   <p>
 
 Template results are now rendered to native Python types.
@@ -276,19 +276,50 @@ homeassistant:
 
 Please note, this is a transitional option, which will be removed in the future.
 
+([@frenck] - [#41227])
+
+  </p>
+</details>
+
+<details>
+  <summary><b>Templates - rate limits</b></summary>
+  <p>
+
 Previously we implemented a rate limit of 1 update per minute for
-`states.DOMAIN` in templates. This works fine for all `states`, however it turned
+`states.DOMAIN` in templates. This has been changed to an update once every second.
-out to be too conservative for `states.DOMAIN` per
-[this comment](https://github.com/home-assistant/architecture/issues/449#issuecomment-711032893).
-Therefore it has been changed to an update once every second.
 
-It is no longer necessary to reference `sensor.time`, `sensor.date`, or manually
+Templates using `states` (without a domain) still have a rate limit of 1 update per minute.
-update template entities that do not listen for state changes, as they will
-automatically update when an referenced entity changes state or every 60 seconds
-after the last state changed event when `now()` or `utcnow()` is contained in
-the template.
 
-([@frenck] - [#41227]) ([@bdraco] - [#42004] [#41147])
+([@bdraco] - [#42004])
+
+  </p>
+
+</details>
+
+<details>
+  <summary><b>Templates - auto-updating `now()`</b></summary>
+  <p>
+The `entity_id:` attribute was recently removed from template entities because
+the templates are now able to find all referenced entities automatically. This
+removal introduced a new problem where templates using the current time could
+no longer use `entity_id: sensor.time` to ensure periodic updates.
+
+With apologies to those who have spent the last couple of releases adding
+workarounds to their templates, we are now introducing an auto-refresh feature
+to time-based templates.
+
+It is thus no longer necessary to reference `sensor.time`, `sensor.date` or manually
+update template entities when `now()` or `utcnow()` is present in the template.
+
+The template will automatically be updated when:
+
+- A referenced entity changes state.
+- At the start of each minute when `now()` or `utcnow()` is present in the template.
+
+Please note, if you have a time-based template where you _do not_ want it to
+update periodically it will now have to be reworked to not use `now()`.
+
+([@bdraco] - [#41147] [#42225])
 
   </p>
 </details>