etcdmain: fix package description for godoc.org

This fixes package description for etcdmain that wasn't compatible with
godoc.org, by deleting the extra blank lines between comment and package name.

etcdmain/doc.go

@@ -12,6 +12,5 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-/* Package etcd contains the main entry point for the etcd binary. */
-
+// Package etcdmain contains the main entry point for the etcd binary.
 package etcdmain