v.help: reorganise the folder layout of the v help topic text files (#17155)

cmd/tools/modules/vhelp/vhelp.v

@@ -5,8 +5,35 @@ import os
 pub fn show_topic(topic string) {
 	vexe := os.real_path(os.getenv('VEXE'))
 	vroot := os.dir(vexe)
-	target_topic := os.join_path(vroot, 'vlib', 'v', 'help', '${topic}.txt')
-	content := os.read_file(target_topic) or {
+	topicdir := os.join_path(vroot, 'vlib', 'v', 'help')
+
+	mut path_to := topic
+	mut topics := os.walk_ext(topicdir, '.txt')
+	mut items := [][]string{}
+
+	// Getting the directory, splitting at `/`, reversing,
+	// trimming to only indexes 0 and 1, and reversing that into the items array
+	for mut item in topics {
+		mut item_rev := item.split('/').reverse()
+		item_rev.trim(2)
+		items << item_rev.reverse()
+	}
+
+	// Getting the path to the help topic text file
+	for cmds in items {
+		if '${topic}.txt' in cmds {
+			path_to = '${cmds[0]}/${cmds[1].replace('.txt', '')}'
+			break
+		}
+	}
+
+	topic_dir := if topic == 'default' {
+		os.join_path(topicdir, 'default.txt')
+	} else {
+		os.join_path(topicdir, '${path_to}.txt')
+	}
+
+	content := os.read_file(topic_dir) or {
 		eprintln('Unknown topic: ${topic}')
 		exit(1)
 	}