Updated from parameter description. (#18852)

Not sure that my description better but origin description looks very weird,
and i try to make emphasize to offset...

docs/reference/search/request-body.asciidoc

@@ -55,7 +55,7 @@ And here is a sample response:
 
 `from`::
 
-    The starting from index of the hits to return. Defaults to `0`.
+    To retrieve hits from a certain offset. Defaults to `0`.
 
 `size`::