Fix links in the docs.

examples/README.md

@@ -8,4 +8,4 @@ requirements.
 * [The "cafe" example](/examples/hello), a "hello world" for Ingress.
 
 * [Self-sharding Varnish cluser](/examples/self-sharding)
-  ([documentation](/docs/self-sharding))
+  ([docs](/docs/self-sharding.md))

examples/self-sharding/README.md

@@ -2,7 +2,7 @@
 
 The manifest in this folder is an example configuration for an Ingress
 with annotations for sharding the cache in a Varnish cluster. See
-[the documentation](/docs/self-sharding) for details.
+[the documentation](/docs/self-sharding.md) for details.
 
 The Ingress may be deployed with the Services from
 [the "cafe" example](/examples/hello).