Clarify docs

Author: odersky

docs/docs/reference/dropped-features/wildcard-init.md

@@ -7,7 +7,7 @@ The syntax
 ```scala
   var x: A = _
 ```
-that was used to indicate an uninitialized field has been dropped.
+that was used to indicate an uninitialized field, has been dropped.
 At its place there is a special value `uninitialized` in the `scala.compiletime` package. To get an uninitialized field, you now write
 ```scala
 import scala.compiletime.uninitialized

library/src/scala/compiletime/package.scala

@@ -20,8 +20,9 @@ package object compiletime {
    *
    *    var x: T = uninitialized
    *
-   *  This signifies that the field is not initialized on its own (On the JVM
-   *  it is still bulk-initialized to a zero bitfield).
+   *  This signifies that the field is not initialized on its own. It is still initialized
+   *  as part of the bulk initialization of the object it belongs to, which assigns zero
+   *  values such as `null`, `0`, `0.0`, `false` to all object fields.
    */
   erased def uninitialized[T]: T = ???