Use magic syntax for godoc NewestSha example.

README.md

@@ -36,7 +36,7 @@ $ go get github.com/conformal/btcdb
   Demonstrates creating a new database and inserting the genesis block into it.
 
 * [NewestSha Example]
-  (http://godoc.org/github.com/conformal/btcdb#example-Db)  
+  (http://godoc.org/github.com/conformal/btcdb#example-Db_newestSha)  
   Demonstrates  querying the database for the most recent best block height and
   hash.
 

example_test.go

@@ -68,7 +68,7 @@ func exampleLoadDB() (btcdb.Db, error) {
 
 // This example demonstrates querying the database for the most recent best
 // block height and hash.
-func ExampleDb() {
+func ExampleDb_newestSha() {
 	// Load a database for the purposes of this example and schedule it to
 	// be closed on exit.  See the CreateDB example for more details on what
 	// this step is doing.