Trim down Seq migration recommendations

Author: dwijnand

_overviews/core/collections-migration-213.md

@@ -60,14 +60,16 @@ available for migrating the usage sites are the following:
 
 The first, in some ways simplest, migration strategy for all non-varargs usages of `scala.Seq` is to replace
 them with `scala.collection.Seq` (and require users to call `.toSeq` or `unsafeWrapArray` when passing such
-sequences to varargs methods).  We recommend, in order of preference, doing such a replacement with one of:
+sequences to varargs methods).
 
-- `import scala.{ collection => sc }` and using `sc.Seq`
-- `import scala.collection.{ Seq => CSeq }` and using `CSeq`
-- replacing `Seq[...]` usage with the fully-qualified `scala.collection.Seq[...]` (e.g. in code gen or macros)
-- `import scala.collection.Seq`, which shadows `scala.Seq` and is a 1-line change, but causes name confusion
+We recommend using `import scala.{ collection => sc }` and using `sc.Seq`, or `import scala.collection.{ Seq =>
+CSeq }` and `CSeq`.
 
-As an example, it would look something like this:
+We recommend against using `import scala.collection.Seq`, which shadows the automatically imported `scala.Seq`,
+because even if it's a oneline change it causes name confusion.  For code generation or macros the safest option
+is using the fully-qualified `_root_.scala.collection.Seq`.
+
+As an example, the migration would look something like this:
 
 ~~~ scala
 import scala.{ collection => sc }