all: fix docs and examples (google/go-cloud#141)

Most notably, adds examples for the blob package.

README.md

@@ -9,6 +9,14 @@ initialization.
 
 [dependency injection]: https://en.wikipedia.org/wiki/Dependency_injection
 
+## Installing
+
+Install `gowire` by running the following inside the Go X Cloud repository:
+
+```shell
+vgo install github.com/google/go-x-cloud/wire/cmd/gowire
+```
+
 ## Basics
 
 Wire has two core concepts: providers and injectors.

cmd/gowire/main.go

@@ -14,7 +14,7 @@
 
 // gowire is a compile-time dependency injection tool.
 //
-// See README.md for an overview.
+// For an overview, see https://github.com/google/go-x-cloud/blob/master/wire/README.md
 package main
 
 import (