Clarify use of alpha characters in @Version (#71)

See violentmonkey/violentmonkey#2353

Author: pointydev

content/pages/api/metadata-block.mdx

@@ -71,7 +71,7 @@ See [more about matching](../matching/).
 
 ### @version
 
-Version of the script, it can be used to check if a script has new versions. It is composed of several parts, joined by `.`. Each part must start with numbers, and can be followed by alphabetic characters.
+Version of the script, it can be used to check if a script has new versions. It is composed of several parts, joined by `.`. Each part must start with numbers, and *can* be followed by alphabetic characters (although these aren't used for version comparison).
 
 **Note:** If no `@version` is specified, the script will not be updated automatically.