Add missing short descriptions, standardize them to start with a capital

Add missing short descriptions, standardize them to start with a capital

	* gobject/tmpl/gclosure.sgml:
	* gobject/tmpl/signals.sgml:
	* gobject/tmpl/gparamspec.sgml:
	* gobject/tmpl/value_collection.sgml:
	* gobject/tmpl/generic_values.sgml:
	* gobject/tmpl/param_value_types.sgml:
	* gobject/tmpl/gboxed.sgml:
	* gobject/tmpl/enumerations_flags.sgml:
	* gobject/tmpl/objects.sgml:
	* gobject/tmpl/gtypemodule.sgml:
	* gobject/tmpl/gtypeplugin.sgml: Add missing short descriptions,
	standardize them to start with a capital and end without a period.

	* glib/tmpl/arrays.sgml:
	* glib/tmpl/memory_chunks.sgml:
	* glib/tmpl/macros.sgml: Remove periods from titles in examples.