Attempt adding ChangeLog entry

doc/ChangeLog

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+Tag name:
+Originator(s): gdicker1
+Date: June 28, 2023
+One-line Summary: Add 60 and 30km MPAS-A meshes for analytic ICs
+Github PR URL:
+
+Purpose of changes (include the issue number and title text for each relevant GitHub issue):
+ - Enable compsets that use analytic ICs and no topography to use 60 and 30km MPAS-A meshes. https://github.com/ESCOMP/CAM/issues/847
+
+Describe any changes made to build system:
+
+Describe any changes made to the namelist:
+
+List any changes to the defaults for the boundary datasets:
+
+Describe any substantial timing or memory changes:
+
+Code reviewed by:
+
+List all files eliminated:
+
+List all files added and what they do:
+
+List all existing files that have been modified, and describe the changes:
+ - Updated bld/namelist_files/namelist_defaults_cam.xml
+
+If there were any failures reported from running test_driver.sh on any test
+platform, and checkin with these failures has been OK'd by the gatekeeper,
+then copy the lines from the td.*.status files for the failed tests to the
+appropriate machine below.  All failed tests must be justified.
+
+cheyenne/intel/aux_cam:
+
+izumi/nag/aux_cam:
+
+izumi/gnu/aux_cam:
+
+CAM tag used for the baseline comparison tests if different than previous
+tag: cam6_3_111
+
+Summarize any changes to answers, i.e.,
+- what code configurations:
+- what platforms/compilers:
+- nature of change (roundoff; larger than roundoff but same climate; new
+  climate):
+
+If bitwise differences were observed, how did you show they were no worse
+than roundoff?
+
+If this tag changes climate describe the run(s) done to evaluate the new
+climate in enough detail that it(they) could be reproduced, i.e.,
+- source tag (all code used must be in the repository):
+- platform/compilers:
+- configure commandline:
+- build-namelist command (or complete namelist):
+- MSS location of output:
+
+MSS location of control simulations used to validate new climate:
+
+URL for AMWG diagnostics output used to validate new climate:
+
+===============================================================
+===============================================================
+
 Tag name: cam6_3_111
 Originator(s): cacraig, hannay, fvitt
 Date: May 17, 2023