Document the bool module in manpages

This adds the manual pages: shtk_bool(3) and shtk_bool_check(3).
Document the cleanup module in manpages

This adds the manual pages: shtk_cleanup(3) and shtk_cleanup_register(3).
Document the cli module in manpages

This adds the manual pages: shtk_cli(3), shtk_cli_dirname(3),
shtk_cli_error(3), shtk_cli_info(3), shtk_cli_progname(3),
shtk_cli_usage_error(3) and shtk_cli_warning(3).
Document the config module in manpages

This adds the manual pages: shtk_config(3), shtk_config_get(3),
shtk_config_get_bool(3), shtk_config_get_default(3), shtk_config_has(3),
shtk_config_include(3), shtk_config_init(3), shtk_config_load(3),
shtk_config_override(3), shtk_config_run_hook(3), shtk_config_set(3) and
shtk_config_unset(3).
Document the cvs module in manpages

This adds the manual pages: shtk_cvs(3), shtk_cvs_checkout(3),
shtk_cvs_fetch(3) and shtk_cvs_update(3).
Document the list module in manpages

This adds the manual pages: shtk_list(3), shtk_list_contains(3) and
shtk_list_filter(3).
Document the process module in manpages

This adds the manual pages: shtk_process(3) and shtk_process_run(3).
Document the version module in manpages

This adds the manual pages: shtk_version(3), shtk_version_at_least(3),
shtk_version_at_most(3) and shtk_version_is(3).
Remove last remaining docstring-like tags

With the conversion of all documentation to manual pages, we have removed
all Doxygen, docstring-like comments from all modules.  Remove the last
remaining instance of this from bootstrap.subr.