Add a sentence about f-interpolator

Author: anatoliykmetyuk

docs/blog/_posts/2019-07-24-17th-dotty-milestone-release.md

@@ -62,12 +62,13 @@ We are making steady progress developing metaprogramming features. The highlight
 
 The removal of 2.12 build marks the stage in Dotty's life when we start to actively use new Dotty features in our code base, making it incompatible with Scala 2.
 
-## Organizational changes
+## Other changes
 There were some organizational and infrastructural changes worth mentioning.
 
 - [Shapeless 3](https://github.com/milessabin/shapeless/tree/shapeless-3) was added to the community build. This means that all the new Dotty features are now tested for the ability to compile Shapeless 3 with them.
 - The process of submitting issues to the Dotty issue tracker is standardized using a GitHub issue template. We have separate templates for bugs, compiler crashes and language feature requests. The latter are now not allowed in the main Dotty repository, and the template for feature requests redirects users to a separate repo meant solely for such requests.
 - Dotty Knowledge Collection initiative. To improve the documentation of the compiler, we came up with an idea of a separate repo where we will log the raw, unrefined knowledge about the compiler internals. This e.g. can be a quick catch we learnt while working that we believe is worth saving somewhere. To read more about the idea, see the [dotty-knowledge](https://github.com/lampepfl/dotty-knowledge) repo's README.
+- `f`-interpolator was implemented as a macro – see the [Scala 2 documentation](https://docs.scala-lang.org/overviews/core/string-interpolation.html#the-f-interpolator) to learn more about what it is.
 
 # Let us know what you think!