ENGDOCS-1965 (#19236)

* ENGDOCS-1965

* Update content/compose/compose-file/13-merge.md

Co-authored-by: Stephanie Aurelio <133041642+stephaurelio@users.noreply.github.com>

---------

Co-authored-by: Stephanie Aurelio <133041642+stephaurelio@users.noreply.github.com>

content/compose/compose-file/13-merge.md

@@ -180,4 +180,28 @@ services:
     read_only: false
     environment: {}
     ports: []
-```
+```
+
+### Replace value
+
+While `!reset` can be used to remove a declaration from a Compose file using an override file, `!override` allows you 
+to fully replace an attribute, bypassing the standard merge rules. A typical example is to fully replace a resource definition, to rely on a distinct model but using the same name.
+
+Merging the following example YAML trees:
+
+```yaml
+networks:
+  foo:
+    # this is production configuration
+    name: production-overlay-network
+    driver: overlay
+    driver-opts: (...)
+```
+
+```yaml
+networks:
+  # this is development configuration
+  foo: !override {}
+```
+
+Results in a Compose application model equivalent to the override YAML tree.