Fix broken links

_posts/2014-06-30-2.12-roadmap.md

@@ -46,7 +46,7 @@ Development of the following features starts in 2015. Since they are binary inco
 * Support for @interface traits, which are guaranteed to compile to Java interfaces (useful for interop, performance and binary compatibility). This is a generalization of the above feature.
 * Streams: integrate into Scala collections? (Anywhere from providing converters to replacing existing functionality.)
 * Use the JDK’s forkjoin library instead of embedding our own. (Switch the global default ExecutionContext to be backed by the ForkJoinPool.commonPool().)
-* [SIP-20](https://docs.scala-lang.org/sips/improved-lazy-val-initialization.html) Improved lazy val initialization (if time allows).
+* [SIP-20](https://github.com/scala/improvement-proposals/pull/19) Improved lazy val initialization (if time allows).
 
 ## Timing
 Scala 2.10.5 (Q4 2014) will be the last 2.10 release. We’re planning five 2.11.x releases in 2014, and a few more in 2015 (we're still deciding on when to EOL 2.11.x). At Typesafe, 2.12 development will begin with infrastructure work in Q4 2014, with our development focus shifting to 2.12 in 2015.

_posts/2015-10-06-release-notes-2.12.0-M3.md

@@ -106,7 +106,6 @@ The following modules have been removed from the Scala 2.12 distribution:
 
 * Scala standard library actors.
   We recommend [Akka actors](https://akka.io/) instead.
-  See the [Scala actors migration guide](https://docs.scala-lang.org/overviews/core/actors-migration-guide.html).
 * Akka actors.
   The Scala distribution and the `scala-library-all` dependency no longer include Akka actors.
   To use Akka, [add it as a dependency](https://doc.akka.io/docs/akka/2.4.0/intro/getting-started.html).

_posts/2016-07-20-sip-summary-minutes.md

@@ -35,7 +35,7 @@ process](https://docs.scala-lang.org/sips/sip-submission.html):
 
 The final SIP discussed one was postponed at the request of the authors:
 
-* **[SIP-22 Async](https://docs.scala-lang.org/sips/async.html)**, Reviewer: Eugene Burmako ([review comments](https://github.com/scala/scala.github.com/pull/213#issuecomment-232940053))
+* **[SIP-22 Async](https://github.com/scala/improvement-proposals/pull/21)**, Reviewer: Eugene Burmako ([review comments](https://github.com/scala/scala.github.com/pull/213#issuecomment-232940053))
 
 In the case of SIP-22, the authors will reopen it when they feel like taking up
 the proposal again, and addressing the issues they must look into next; in

_posts/2016-08-15-sip-meeting-august-results.md

@@ -16,14 +16,14 @@ The other two progressed and will have a follow-up iteration.
 
 The rejected proposals were:
 
--   [SIP-12: Uncluttering Scala's syntax for control structures](https://docs.scala-lang.org/sips/uncluttering-control.html).
+-   [SIP-12: Uncluttering Scala's syntax for control structures](https://github.com/scala/improvement-proposals/pull/12).
     Originally proposed in 2011. The proposal suggested syntax changes
     in if's, for and while loops, moving Scala's syntax away from Java
     and C-like languages. Whereas such changes may be arguably more
     beautiful, the Committee agreed that would give more problems
     than benefits. Seth Tisue, the appointed reviewer, fully explains
     the Committee's reaction [here](https://github.com/scala/scala.github.com/issues/555).
--   [SIP-16: Self-cleaning macros](https://docs.scala-lang.org/sips/self-cleaning-macros.html).
+-   [SIP-16: Self-cleaning macros](https://github.com/scala/improvement-proposals/pull/15).
     Originally proposed in 2012. Macros add a whole new dimension to the
     Scala language. Their experimental implementation was adopted by a
     lot of Scala libraries and were immensely useful for the creation
@@ -52,9 +52,9 @@ speaking up and collaborating with the process—your vibrant
 responses will greatly enrich our future deliberations.
 
 Next month, we’ll discuss five more proposals, including
-[SIP-21: Spores](https://docs.scala-lang.org/sips/spores.html) and
+[SIP-21: Spores](https://github.com/scala/improvement-proposals/pull/20) and
 [SIP-24: Repeated by-name
-parameters](https://docs.scala-lang.org/sips/repeated-byname.html).
+parameters](https://github.com/scala/improvement-proposals/pull/23).
 We hope to finish off the list of old proposals in the queue and focus
 ourselves on the most recent proposals and the ones that are to
 come!

_posts/2017-10-09-scalamacros.md

@@ -298,7 +298,7 @@ as a community, can stand up to the challenge to complete this project to end.
 [minutes]: https://scala.epfl.ch/minutes/2017/09/12/september-12-2017.html
 [SCP-014]: https://scala.epfl.ch/minutes/2017/09/12/september-12-2017.html#scp-014-production-ready-scalamacrosscalamacros
 [SIP-16]: https://github.com/scala/docs.scala-lang/pull/57#issuecomment-239210760
-[SIP-29]: https://docs.scala-lang.org/sips/inline-meta.html#losing-whiteboxity
+[SIP-29]: https://github.com/scala/improvement-proposals/pull/28
 [SIP]: https://docs.scala-lang.org/sips/index.html
 ["Two Approaches to Portable Macros"]: https://www.dropbox.com/s/2xzcczr3q77veg1/gestalt.pdf
 [whitebox def macros]: https://contributors.scala-lang.org/t/pre-sip-whitebox-def-macros/1210