fix dead links

fixes scala#1101

Author: SethTisue

contribute/bug-reporting-guide.md

@@ -44,7 +44,7 @@ If you have a code snippet that is resulting in bytecode which you believe is be
 
    5. If you want to file an improvement in the issue tracker please discuss it first on one of the mailing lists. They offer much bigger audience than issue tracker. The latter is not suitable for long discussions.
 
-* Keep in mind that the behavior you are witnessing could be intended. Good formal resources for verifying whether or not the language behavior is intended is either in the [Scala Improvement Proposal Documents](http://docs.scala-lang.org/sips/sip-list.html) or in the [Scala Language Specification](http://www.scala-lang.org/files/archive/spec/2.13/). If in doubt, you may always ask on the [Community Category](https://contributors.scala-lang.org/c/community) or [Stack Overflow](https://stackoverflow.com/questions/tagged/scala).
+* Keep in mind that the behavior you are witnessing could be intended. Good formal resources for verifying whether or not the language behavior is intended is either in the [Scala Improvement Proposal Documents](https://docs.scala-lang.org/sips/) or in the [Scala Language Specification](http://www.scala-lang.org/files/archive/spec/2.13/). If in doubt, you may always ask on the [Community Category](https://contributors.scala-lang.org/c/community) or [Stack Overflow](https://stackoverflow.com/questions/tagged/scala).
 
 In general, if you find yourself stuck on any of these steps, asking on [Scala Contributors](https://contributors.scala-lang.org/) can be helpful:
 

contribute/corelibs.md

@@ -20,4 +20,4 @@ There are several options for contributing to Scala's core libraries. You can:
 For significant new functionality or a whole new API to be considered for
 inclusion in the core Scala distribution, you will be asked to submit a SLIP (Scala Library Improvement Process) document.
 
-Please see [instructions for submitting a new SLIP](http://docs.scala-lang.org/sips/slip-submission.html) and familiarize yourself with the [SIP/SLIP](http://docs.scala-lang.org/sips/) section of the Scala documentation site. Also please pay particular attention to the [pre-requisites](http://docs.scala-lang.org/sips/slip-submission.html) before submitting a SLIP.
+Please see [instructions for submitting a new SLIP](https://web.archive.org/web/20180116192845/http://docs.scala-lang.org/sips/slip-submission.html) and familiarize yourself with the [SIP/SLIP](http://docs.scala-lang.org/sips/) section of the Scala documentation site. Also please pay particular attention to the [pre-requisites](http://docs.scala-lang.org/sips/slip-submission.html) before submitting a SLIP.