update docs

docs/rules/ExplicitResultTypes.md

@@ -4,8 +4,7 @@ id: ExplicitResultTypes
 title: ExplicitResultTypes
 ---
 
-This rewrite inserts type annotations for inferred public members. Only compatible with 
-scala 2.12 & 2.13.
+This rewrite inserts type annotations for inferred public members.
 
 Example:
 
@@ -35,6 +34,9 @@ This rule has several known limitations, which are most likely fixable with some
 effort. At the time of this writing, there are no short-term plans to address
 these issues however.
 
+Scala 3 support is recent and therefore not widely tested. Expect annotations
+to be be less precise than the ones added to sources compiled with Scala 2.x.
+
 ### Imports ordering
 
 The rewrite inserts imports at the bottom of the global import list. Users are
@@ -43,8 +45,8 @@ expected to organize the imports according to the conventions of their codebase.
 For example, the rewrite may produce the following diff.
 
 ```diff
-import java.io.File
-import scala.collection.mutable
+  import java.io.File
+  import scala.collection.mutable
 + import java.util.UUID
 ```