Add DOI for model user manual

Author: anton-seaice

README.md

@@ -7,9 +7,10 @@ More recent versions are found in the [CICE](https://github.com/CICE-Consortium/
 
 If you expect to make any changes to the code, we recommend that you work in the CICE and Icepack repositories.  Changes made to code in this repository will not be accepted, other than critical bug fixes.
 
-There is [PDF documentation](https://github.com/ACCESS-NRI/cice5/blob/master/doc/cicedoc.pdf) available for CICE 5.1.2, however some changes were made to this fork to support coupling with ACCESS-OM2 and ACCESS-ESM1.6, Parallel IO, ERA5 Forcing, BGC modelling and for other updates. Some of these changes are described in the [ACCESS-OM2 Technical Report](https://github.com/COSIMA/ACCESS-OM2-1-025-010deg-report).
+There is [PDF documentation](https://github.com/ACCESS-NRI/cice5/blob/master/doc/cicedoc.pdf)([DOI](https://doi.org/10.5281/zenodo.19207490)) available for CICE 5.1.2, however some changes were made to this fork to support coupling with ACCESS-OM2 and ACCESS-ESM1.6, Parallel IO, ERA5 Forcing, BGC modelling and for other updates. Some of these changes are described in the [ACCESS-OM2 Technical Report](https://github.com/COSIMA/ACCESS-OM2-1-025-010deg-report).
 
 ## Useful links
+
 * **Wiki**: https://github.com/CICE-Consortium/CICE-svn-trunk/wiki
 
    Information about the CICE model prior to version 6 including how to obtain the code