Add compiler plugin section

Author: allanrenucci

docs/blog/_posts/2018-07-06-ninth-dotty-milestone-release.md

@@ -33,11 +33,13 @@ support for sbt 1, introduced improved unchecked warnings and improved SAM type
 The REPL now uses [JLine 3](https://github.com/jline/jline3) under the hood which improves on
 many aspects such as auto-completions and multi-line editing. The REPL now also works on Windows!
 
+
 ### Documentation support in the IDE [#4461](https://github.com/lampepfl/dotty/pull/4461), [#4648](https://github.com/lampepfl/dotty/pull/4648)
 The Dotty IDE will now display documentation on code hover for symbols that were previously
 compiled by the Dotty compiler. In the future, we plan to let users query the documentation
 in the REPL as well.
 
+
 ### Drop requirement that implicit functions must be non-empty [#4549](https://github.com/lampepfl/dotty/pull/4549)
 We decided to remove an arbitrary restriction that implicit and functions must be non-empty.
 We can now write:
@@ -50,8 +52,8 @@ val prod2: IntProducer = 2
 
 An interesting observation is that by-name parameters can now be encoded as implicit function types:
 ```scala
-def timed[T](op: => T) = ...
-def timed[T](op: implicit () => T) = ...
+def timed[T](op: => T): T = ...
+def timed[T](op: implicit () => T): T = ...
 
 timed {
   fetch(url)
@@ -60,6 +62,7 @@ timed {
 
 Both definitions above are equivalent.
 
+
 ### Emit feature warnings for implicit conversions [#4229](https://github.com/lampepfl/dotty/pull/4229)
 Implicit conversions are easily the most misused feature in Scala. We now emit feature warnings
 when encountering an implicit conversion definition, just like Scala 2 does.
@@ -69,22 +72,37 @@ unless the conversion is an implicit class, or otherwise co-defined with the typ
 to which it converts, or the conversion is predefined in `scala.Predef` or is the
 `scala.reflect.Selectable.reflectiveSelect` conversion (we might extend this to more conversions).
 
-### Optimise s and raw interpolators [#3961](https://github.com/lampepfl/dotty/pull/4229)
+
+### Optimise s and raw interpolators [#3961](https://github.com/lampepfl/dotty/pull/3961)
 `s` and `raw` string interpolators were known to be slower than their not type-safe counterparts:
 ```scala
 s"Hello $name!"
 
-// versus
+// compared to:
 "Hello " + name + "!"
 ```
 The compiler will now desugar the former into the later. Special thanks to
 [Wojtek Swiderski](https://github.com/Wojtechnology) who contributed this feature to the Dotty
 compiler!
 
+
+### Support for compiler plugins [#3438](https://github.com/lampepfl/dotty/pull/#3438)
+Dotty now supports Compiler plugins. Compiler plugins let you customise the compiler pipeline
+without having to modify the compiler source code. A major difference compared to Scala 2 is
+that Dotty plugins must run after the type checker. Being able to influence normal type checking
+is a very powerful feature but for production usages, a predictable and consistent type checker
+is more important.
+
+Starting with 1.1.5 Dotty compiler plugins can be used with `sbt`. Please refer to the `sbt`
+[documentation](https://www.scala-sbt.org/1.x/docs/Compiler-Plugins.html) for more information.
+
+For more information, visit the [Compiler Plugin](http://dotty.epfl.ch/docs/reference/changed/compiler-plugins.html)
+section of our documentation.
+
 ## Trying out Dotty
 
 ### sbt
-Using sbt 1.1.4 or newer, do:
+Using sbt 1.1.5 or newer, do:
 
 ```shell
 sbt new lampepfl/dotty.g8