Clarify that we are not using the old dottydoc tool anymore

Author: anatoliykmetyuk

docs/blog/_posts/2020-12-18-scala3-m3.md

@@ -125,7 +125,9 @@ The change involved an extensive discussion which you can read in the [PR #10670
 # Tooling improvements
 As the work on Scala 3 gets closer to the stable release, the focus increasingly shifts on the tooling available to get started with Scala 3.
 
-As part of the tooling effort, Scala 3 documentation tool is rapidly improved. [PR #10522](https://github.com/lampepfl/dotty/pull/10522) proves that the doctool can generate documentation for the community build projects.
+For a while now, we are not using the old dottydoc documentation tool for building the documentation. We are developing an entirely new tool, scala3doc, from scratch.
+
+As part of the tooling effort, this new Scala 3 documentation tool is rapidly improved. [PR #10522](https://github.com/lampepfl/dotty/pull/10522) proves that the doctool can generate documentation for the community build projects.
 
 [PR #10491](https://github.com/lampepfl/dotty/pull/10491) introduced the scripting capability to Scala 3. Consider the following source named e.g. `Main.scala`: