tools/vcheck-md: add -skip_line_length_check flag and fix vmod handling in '```vmod' (#17997)

cmd/tools/vcheck-md.v

@@ -50,6 +50,7 @@ fn main() {
 		println('´-all´ flag is deprecated. Please use ´v check-md .´ instead.')
 		exit(1)
 	}
+	mut skip_line_length_check := '-skip-line-length-check' in os.args
 	if show_progress {
 		// this is intended to be replaced by the progress lines
 		println('')
@@ -76,6 +77,7 @@ fn main() {
 			continue
 		}
 		mut mdfile := MDFile{
+			skip_line_length_check: skip_line_length_check
 			path: file_path
 			lines: lines
 		}
@@ -157,6 +159,7 @@ enum MDFileParserState {
 
 struct MDFile {
 	path                   string
+	skip_line_length_check bool
 mut:
 	lines    []string
 	examples []VCodeExample
@@ -176,6 +179,7 @@ fn (mut f MDFile) check() CheckResult {
 	mut anchor_data := AnchorData{}
 	for j, line in f.lines {
 		// f.progress('line: $j')
+		if !f.skip_line_length_check {
 			if f.state == .vexample {
 				if line.len > too_long_line_length_example {
 					wprintln(wline(f.path, j, line.len, 'example lines must be less than ${too_long_line_length_example} characters'))
@@ -205,6 +209,7 @@ fn (mut f MDFile) check() CheckResult {
 				eprintln(line)
 				res.errors++
 			}
+		}
 		if f.state == .markdown {
 			anchor_data.add_links(j, line)
 			anchor_data.add_link_targets(j, line)
@@ -602,6 +607,8 @@ fn (mut f MDFile) check_examples() CheckResult {
 				'play' {}
 				// same as play, but run example as a test
 				'play-test' {}
+				// when ```vmod
+				'mod' {}
 				else {
 					eprintln(eline(f.path, e.sline, 0, 'unrecognized command: "${command}", use one of: wip/ignore/compile/failcompile/okfmt/nofmt/oksyntax/badsyntax/cgen/globals/live/shared'))
 					should_cleanup_vfile = false