Release notes: Add historical tag, and spell fix

1.  Add missing [File Change] tag to old 4.4.1-RC1 release note which modified hdf5 file format control.
2.  Minor spelling fix, coincidental.

RELEASE_NOTES.md

@@ -465,7 +465,7 @@ See [GitHub #1251](https://github.com/Unidata/netcdf-c/issues/1251).
 
 ### 4.4.1-RC1 - April 15, 2016
 
-* [Bug Fix][Enhancement] Fixed an issue with netCDF4 files generated using version `1.10.0` of the HDF5 library.  The 1.10 release potentially changed the underlying file format, introducing a backwards compatibility issue with the files generated.  HDF5 provided an API for retaining the 1.8.x file format, which is now on by default.  See [GitHub Issue #250](https://github.com/Unidata/netcdf-c/issues/250) for more information.
+* [Bug Fix][Enhancement][File Change] Fixed an issue with netCDF4 files generated using version `1.10.0` of the HDF5 library.  The 1.10 release potentially changed the underlying file format, introducing a backwards compatibility issue with the files generated.  HDF5 provided an API for retaining the 1.8.x file format, which is now on by default.  See [GitHub Issue #250](https://github.com/Unidata/netcdf-c/issues/250) for more information.
 * [Bug Fix] Corrected an issue with autotools-based builds performed out-of-source-tree.  See [GitHub Issue #242](https://github.com/Unidata/netcdf-c/issues/242) for more information.
 * [Enhancement] Modified `nc_inq_type()` so that it would work more broadly without requiring a valid ncid.  See [GitHub Issue #240](https://github.com/Unidata/netcdf-c/issues/240) for more information.
 * [Enhancement] Accepted a patch code which added a hashmap lookup for rapid var and dim retrieval in nc3 files, contributed by Greg Sjaardema.  See [GitHub Pull Request #238](https://github.com/Unidata/netcdf-c/pull/238) for more information.
@@ -519,7 +519,7 @@ See [GitHub #1251](https://github.com/Unidata/netcdf-c/issues/1251).
     2. Given #1, then the NC_PNETCDF mode flag becomes a subset of NC_MPIIO, so made NC_PNETCDF an alias for NC_MPII.
     3. NC_FORMAT_64BIT is now deprecated.  Use NC_FORMAT_64BIT_OFFSET.
 
-Further information regarding the CDF-5 file format specifrication may be found here: http://cucis.ece.northwestern.edu/projects/PnetCDF/CDF-5.html
+Further information regarding the CDF-5 file format specification may be found here: http://cucis.ece.northwestern.edu/projects/PnetCDF/CDF-5.html
 
 * Modified configure.ac to provide finer control over parallel
   support. Specifically, add flags for: