Add a section about vararg splices

Author: anatoliykmetyuk

docs/blog/_posts/2021-02-17-scala3-rc1.md

@@ -60,6 +60,9 @@ import NumPy as np
 
 For the details and discussion, see [PR #11244](https://github.com/lampepfl/dotty/pull/11244). Read more about this change in the [documentation](https://dotty.epfl.ch/docs/reference/changed-features/imports.html).
 
+# Use `*` for vararg splices.
+[PR #11240](https://github.com/lampepfl/dotty/pull/11240) changed the syntax of vararg splices in patterns and function arguments. The new syntax uses a postfix `*`, instead of `: _*`, analogously to how a vararg parameter is declared.
+
 # Use `uninitialized` for wildcard initializers
 An obscure use of `_` occurs in var definitions: