[DOCS] Fix term for partially mounted indices

Author: jrodewig

docs/reference/release-notes/highlights.asciidoc

@@ -45,9 +45,9 @@ Other versions:
 [[frozen-tier-ga]]
 === Frozen tier is now GA
 
-The frozen tier and partially mounted {search-snaps}, formerly known as
-shared-cache {search-snaps}, are now generally available. We these features as
-technical previews in 7.12. See the
+The frozen tier and partially mounted indices, formerly known as shared cache
+{search-snaps}, are now generally available. We these features as technical
+previews in 7.12. See the
 {ref-bare}/7.12/release-highlights.html#frozen-tier-shared-snapshot-cache[7.12
 announcement].