[DOCS] Change prev version to 7.5 in upgrade docs (#48415)

Author: jrodewig

docs/reference/upgrade.asciidoc

@@ -18,7 +18,7 @@ The following table shows the recommended upgrade paths to {version}.
 |Upgrade from   
 |Recommended upgrade path  to {version}
 
-|7.0–7.4
+|7.0–7.5
 |<<rolling-upgrades,Rolling upgrade>> to {version}
 
 |6.8