chore: update support policy wording (#1979)

README.md

@@ -579,12 +579,8 @@ following lifecycle regarding support for a major version:
 wouldn’t otherwise introduce a breaking change). New major versions are
 guaranteed to be "active" for a minimum of 1 year.
 
-- **Deprecated** - Deprecated versions continue to receive security and critical
-bug fixes, but do not receive new features. Deprecated versions will be publicly
-supported for 1 year.
-
-- **Unsupported** - Any major version that has been deprecated for >=1 year is
-considered publicly unsupported.
+- **Maintenance** - Maintenance versions continue to receive security and critical
+bug fixes, but do not receive new features.
 
 ### Release cadence