docs: clarify what fixes are merged to LTS versions (#38788)

PR Close #38788

aio/content/guide/releases.md

@@ -94,7 +94,7 @@ All of our major releases are supported for 18 months.
 
 * 6 months of *active support*, during which regularly-scheduled updates and patches are released.
 
-* 12 months of *long-term support (LTS)*, during which only critical fixes and security patches are released.
+* 12 months of *long-term support (LTS)*, during which only [critical fixes and security patches](#lts-fixes) are released.
 
 The following table provides the status for Angular versions under support.
 
@@ -107,6 +107,13 @@ Version | Status | Released     | Active Ends  | LTS Ends
 
 Angular versions ^4.0.0, ^5.0.0, ^6.0.0 and ^7.0.0 are no longer under support.
 
+### LTS fixes
+
+As a general rule, a fix is considered for an LTS version if it resolves one of:
+
+* a newly identified security vulnerability,
+* a regression, since the start of LTS, caused by a 3rd party change, such as a new browser version.
+
 {@a deprecation}
 ## Deprecation practices