Remove experimental macro feature mention

Co-authored-by: Nicolas Stucki <nicolas.stucki@gmail.com>

Author: anatoliykmetyuk

docs/blog/_posts/2021-06-07-scala3.0.1-rc1-release.md

@@ -68,7 +68,6 @@ A lot of metaprogramming work was focused on improving the performance. Some of
 - Improve quote matcher performance [#12418](https://github.com/lampepfl/dotty/pull/12418)
 - Port scala.quoted.runtime.impl.QuoteMatcher [#12402](https://github.com/lampepfl/dotty/pull/12402)
 
-A way to abort macro expansion was enhanced in PR [#12056](https://github.com/lampepfl/dotty/pull/12056). Now you can use `errorAndAbort(msg: String)` to stop macro expansion with an error, and `expr.valueOrAbort` to abort macro expansion if a given expression doesn't represent a value or possibly contains side effects.
 
 # Issue fixing
 Otherwise, we are making an effort to reduce our issue tracker. Among others, the following are some of the PRs dedicated to issue fixing: