[DOCS] Expose URI parts processor in Painless (#73896)

docs/painless/painless-guide/painless-ingest.asciidoc

@@ -96,3 +96,14 @@ supplied in the `value` parameter.
 ----
 String urlDecode(String value);
 ----
+
+===== URI decomposition
+Use the {ref}/uri-parts-processor.html[URI parts processor] to decompose the URI string
+supplied in the `value` parameter. Returns a map of key-value pairs in which the key is
+the name of the URI component such as `domain` or `path` and the value is the
+corresponding value for that component.
+
+[source,Painless]
+----
+String uriParts(String value);
+----