Address reviewer comments

Author: allanrenucci

docs/blog/_posts/2017-10-02-fourth-dotty-milestone-release.md

@@ -47,14 +47,13 @@ to provide syntax highlighting, multi-line editing, history, etc.
 Since our first release, it has been possible to use Scala 2 libraries in a
 Dotty project as explained in the
 [dotty-example-project](https://github.com/smarter/dotty-example-project#getting-your-project-to-compile-with-dotty).
-Previously, we supported libraries compiled Scala 2.11, but starting with this
+Previously, we supported libraries compiled by Scala 2.11, but starting with this
 release we support Scala 2.12 instead. If your Dotty project has Scala 2
 dependencies this change should be transparent for you assuming all your
 dependencies have been published for 2.12.
 
 ### Performance work
-Over the last few weeks, we have begun work on improving compilation bit by bit
-with some good results:
+Over the last few weeks, we started working on compilation speed with some good results:
 compiling [ScalaPB](https://github.com/dotty-staging/scalapb) is now 20% faster
 than with Dotty 0.3.0-RC2. You can follow along our progress on
 http://dotty-bench.epfl.ch/.
@@ -112,17 +111,17 @@ According to `git shortlog -sn --no-merges 0.3.0-RC1..0.4.0-RC1` these are:
    TODO
 ```
 
-If you want to get your hands dirty with any of this, now is a good moment to get involved!
-You can have a look at our [Getting Started page](http://dotty.epfl.ch/docs/contributing/getting-started.html),
-our [Awesome Error Messages](http://scala-lang.org/blog/2016/10/14/dotty-errors.html) or some of
+If you want to get your hands dirty and contribute to Dotty, now is a good time to get involved!
+You can have a look at our [Getting Started page for new contributors](http://dotty.epfl.ch/docs/contributing/getting-started.html),
+the [Awesome Error Messages](http://scala-lang.org/blog/2016/10/14/dotty-errors.html) project or some of
 the simple [Dotty issues](https://github.com/lampepfl/dotty/issues?q=is%3Aissue+is%3Aopen+label%3Aexp%3Anovice).
 They make perfect entry-points into hacking on the compiler.
 
 We are looking forward to having you join the team of contributors.
 
 ## Library authors: Join our community build
-Dotty now has a set of libraries that are built against every nightly snapshot.
-Currently this includes ScalaPB, algebra, scalatest, scopt and squants.
+Dotty now has a set of widely-used community libraries that are built against every nightly Dotty
+snapshot. Currently this includes ScalaPB, algebra, scalatest, scopt and squants.
 Join our [community build](https://github.com/lampepfl/dotty-community-build)
 to make sure that our regression suite includes your library.