Docs: Remove reference to imaginary "no_docs_query"

No reference to it in the source code except this file.

Closes #8566

docs/reference/query-dsl/queries/query-string-syntax.asciidoc

@@ -292,6 +292,5 @@ being touched by the query string parser: `"wi\ fi"`.
 
 ===== Empty Query
 
-If the query string is empty or only contains whitespaces the
-query string is interpreted as a `no_docs_query` and will yield
-an empty result set. 
+If the query string is empty or only contains whitespaces the query will
+yield an empty result set.