Added {album}, {keyword}, and {person} to template system

utils/build_help_table.py

@@ -1,8 +1,14 @@
 """ Builds the template table in markdown format for README.md """
 
-from osxphotos.template import TEMPLATE_SUBSTITUTIONS
+from osxphotos.template import (
+    TEMPLATE_SUBSTITUTIONS,
+    TEMPLATE_SUBSTITUTIONS_MULTI_VALUED,
+)
 
 print("| Substitution | Description |")
 print("|--------------|-------------|")
-for subst, descr in TEMPLATE_SUBSTITUTIONS.items():
+for subst, descr in [
+    *TEMPLATE_SUBSTITUTIONS.items(),
+    *TEMPLATE_SUBSTITUTIONS_MULTI_VALUED.items(),
+]:
     print(f"|{subst}|{descr}|")