Add missing reference docs for platform directives

Author: Gedochao

modules/directives/src/main/scala/scala/build/preprocessing/directives/Platform.scala

@@ -21,10 +21,12 @@ import scala.cli.commands.SpecificationLevel
 
 @DirectiveGroupName("Platform")
 @DirectiveExamples("//> using platform scala-js")
-@DirectiveExamples("//> using platform jvm scala-native")
+@DirectiveExamples("//> using platforms jvm scala-native")
 @DirectiveUsage(
   "//> using platform (jvm|scala-js|js|scala-native|native)+",
-  "`//> using platform` (`jvm`|`scala-js`|`js`|`scala-native`|`native`)+"
+  """`//> using platform` (`jvm`|`scala-js`|`js`|`scala-native`|`native`)+
+    |`//> using platforms` (`jvm`|`scala-js`|`js`|`scala-native`|`native`)+
+    |""".stripMargin
 )
 @DirectiveDescription("Set the default platform to Scala.js or Scala Native")
 @DirectiveLevel(SpecificationLevel.SHOULD)

website/docs/reference/directives.md

@@ -290,11 +290,13 @@ Set parameters for packaging
 Set the default platform to Scala.js or Scala Native
 
 `//> using platform` (`jvm`|`scala-js`|`js`|`scala-native`|`native`)+
+`//> using platforms` (`jvm`|`scala-js`|`js`|`scala-native`|`native`)+
+
 
 #### Examples
 `//> using platform scala-js`
 
-`//> using platform jvm scala-native`
+`//> using platforms jvm scala-native`
 
 ### Publish
 

website/docs/reference/scala-command/directives.md

@@ -226,11 +226,13 @@ Add Javac options which will be passed when compiling sources.
 Set the default platform to Scala.js or Scala Native
 
 `//> using platform` (`jvm`|`scala-js`|`js`|`scala-native`|`native`)+
+`//> using platforms` (`jvm`|`scala-js`|`js`|`scala-native`|`native`)+
+
 
 #### Examples
 `//> using platform scala-js`
 
-`//> using platform jvm scala-native`
+`//> using platforms jvm scala-native`
 
 ### Repository