Help: Add notes for topic 'ExternalProject_exclude-from-all'

Help/release/dev/ExternalProject_exclude-from-all.rst

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+ExternalProject_exclude-from-all
+--------------------------------
+
+* The :module:`ExternalProject` module ``ExternalProject_Add`` command
+  learned a new ``EXCLUDE_FROM_ALL`` option to cause the external
+  project target to have the :prop_tgt:`EXCLUDE_FROM_ALL` target
+  property set.
+
+* The :module:`ExternalProject` module ``ExternalProject_Add_Step`` command
+  learned a new ``EXCLUDE_FROM_MAIN`` option to cause the step to not be
+  a direct dependency of the main external project target.