updating README (ufs-community#333)

* updating README

* update reame.md

Fixes ufs-community#333

Co-authored-by: George Gayno <[email protected]>

README.md

@@ -51,6 +51,49 @@ make -j2
 make install
 ```
 
+## Contents
+
+The UFS_UTILS package contains the following utilities (under the sorc
+directory):
+- chgres_cube
+- emcsfc_ice_blend
+- emcsfc_snow2mdl
+- fre-nctools
+- fvcom_tools
+- global_chgres
+- global_cycle
+- grid_tools
+- nst_tf_chg
+- orog_mask_tools
+- sfc_climo_gen
+- vcoord_gen
+
+The reg_tests directory contains the regression test code.
+
+The fix directory is where we set links to directories containing
+large, static data files used by UFS_UTILS programs.
+
+The tests directory contains unit tests.
+
+The ush directory contains scripts to run UFS_UTILS programs.  Most are called from
+driver scripts.
+
+The util directory contains utility scripts to create coldstart initial conditions
+for GFS parallels, and to run the vertical coordinate generator.
+
+The parm directory contains variable mapping parameter tables used by the chgres_cube program.
+
+The driver_scripts directory contains high-level driver scripts to create a model
+grid on officially supported HPC platforms.
+
+The modulefiles directory contains modules loaded when building UFS_UTILS on supported
+HPC platforms.  They are also loaded at runtime by utility and regression test scripts.
+
+The docs directory contains the control file for the doxygen
+documentation build, as well as some markdown files which are part of
+the documentation. It also contains (in the source subdirectory) the
+ReadTheDocs documentation files.
+
 ## Disclaimer
 
 The United States Department of Commerce (DOC) GitHub project code is