clarify the package name (#660)

* clarify the package name

* Adding import and connection string sections

* more clarification around the go usage

Author: khash

README.md

@@ -141,7 +141,7 @@ func main() {
     m, err := migrate.NewWithDatabaseInstance(
         "file:///migrations",
         "postgres", driver)
-    m.Steps(2)
+    m.Up() // or m.Step(2) if you want to explicitly set the number of migrations to run
 }
 ```
 

source/google_cloud_storage/README.md

@@ -1,3 +1,14 @@
-# google_cloud_storage
+# Google Cloud Storage
+
+
+## Import
+
+```go
+import (
+  _ "github.com/golang-migrate/migrate/v4/source/google_cloud_storage"
+ )
+ ```
+
+## Connection String
 
 `gcs://<bucket>/<prefix>`