Docs: Update query-string-syntax.asciidoc

Closes #6253

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

@@ -135,7 +135,7 @@ curly brackets `{min TO max}`.
 
 * All days in 2012:
 
-    date:[2012/01/01 TO 2012/12/31]
+    date:[2012-01-01 TO 2012-12-31]
 
 * Numbers 1..5
 
@@ -151,7 +151,7 @@ curly brackets `{min TO max}`.
 
 * Dates before 2012
 
-    date:{* TO 2012/01/01}
+    date:{* TO 2012-01-01}
 
 Curly and square brackets can be combined: