fix file ending

Author: willow-ahrens

spec/latest/index.bs

@@ -546,4 +546,5 @@ manner, using the corresponding dataset names previously defined.
 Supported Binary Containers {#supported_containers}
 ---------------------------------------------------
 
-Currently supported binary containers include HDF5 and NetCDF (but should include more).
+Currently supported binary containers include HDF5 and NetCDF (but should include more).
+