doc: link to self-hosted articles from docs.html

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5685061

doc/docs.html

@@ -87,11 +87,11 @@ Guided tours of Go programs.
 <ul>
 <li><a href="http://blog.golang.org/2010/04/json-rpc-tale-of-interfaces.html">JSON-RPC: a tale of interfaces</a></li>
 <li><a href="http://blog.golang.org/2010/07/gos-declaration-syntax.html">Go's Declaration Syntax</a></li>
-<li><a href="http://blog.golang.org/2010/08/defer-panic-and-recover.html">Defer, Panic, and Recover</a></li>
+<li><a href="/doc/articles/defer_panic_recover.html">Defer, Panic, and Recover</a></li>
 <li><a href="http://blog.golang.org/2010/09/go-concurrency-patterns-timing-out-and.html">Go Concurrency Patterns: Timing out, moving on</a></li>
-<li><a href="http://blog.golang.org/2011/01/go-slices-usage-and-internals.html">Go Slices: usage and internals</a></li>
+<li><a href="/doc/articles/slices_usage_and_internals.html">Go Slices: usage and internals</a></li>
 <li><a href="http://blog.golang.org/2011/05/gif-decoder-exercise-in-go-interfaces.html">A GIF decoder: an exercise in Go interfaces</a></li>
-<li><a href="http://blog.golang.org/2011/07/error-handling-and-go.html">Error Handling and Go</a></li>
+<li><a href="/doc/articles/error_handling.html">Error Handling and Go</a></li>
 </ul>
 
 <h3>Packages</h3>