doc: global options are rarely flagged

[jsoref]

This mentions that there's such a thing as global options:

curl/docs/cmdline-opts/next.d

Lines 15 to 17 in 3085ccf

	--next will reset all local options and only global ones will have their
	values survive over to the operation following the --next instruction. Global
	options include --verbose, --trace, --trace-ascii and --fail-early.

This tells us that it is one:

curl/docs/cmdline-opts/fail-early.d

Line 18 in 3085ccf

This option is global and does not need to be specified for each use of --next.

None of these do:

curl/docs/cmdline-opts/trace-ascii.d

Lines 7 to 15 in 3085ccf

	Enables a full trace dump of all incoming and outgoing data, including
	descriptive information, to the given output file. Use "-" as filename to have
	the output sent to stdout.
	This is very similar to --trace, but leaves out the hex part and only shows
	the ASCII part of the dump. It makes smaller output that might be easier to
	read for untrained humans.
	If this option is used several times, the last one will be used.

curl/docs/cmdline-opts/trace-time.d

Line 6 in 3085ccf

Prepends a time stamp to each trace or verbose line that curl displays.

curl/docs/cmdline-opts/trace.d

Lines 7 to 12 in 3085ccf

	Enables a full trace dump of all incoming and outgoing data, including
	descriptive information, to the given output file. Use "-" as filename to have
	the output sent to stdout. Use "%" as filename to have the output sent to
	stderr.
	If this option is used several times, the last one will be used.

curl/docs/cmdline-opts/verbose.d

Lines 8 to 20 in 3085ccf

	Makes curl verbose during the operation. Useful for debugging and seeing
	what's going on "under the hood". A line starting with '>' means "header data"
	sent by curl, '<' means "header data" received by curl that is hidden in
	normal cases, and a line starting with '*' means additional info provided by
	curl.
	If you only want HTTP headers in the output, --include might be the option
	you're looking for.
	If you think this option still doesn't give you enough details, consider using
	--trace or --trace-ascii instead.
	Use --silent to make curl really quiet.

Can't tell if these count:

curl/docs/cmdline-opts/silent.d

Lines 7 to 12 in 3085ccf

	Silent or quiet mode. Don't show progress meter or error messages. Makes Curl
	mute. It will still output the data you ask for, potentially even to the
	terminal/stdout unless you redirect it.
	Use --show-error in addition to this option to disable progress meter but
	still show error messages.

curl/docs/cmdline-opts/show-error.d

Line 7 in 3085ccf

When used with --silent, it makes curl show an error message if it fails.