Added help command

cmd/cmsh/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"fmt"
 	"github.com/chzyer/readline"
 	"log"
 	"ucl.lmika.dev/repl"
@@ -22,13 +23,24 @@ func main() {
 	)
 	ctx := context.Background()
 
+	instRepl.SetCommand("hello", func(ctx context.Context, args ucl.CallArgs) (any, error) {
+		fmt.Println("hello")
+		return nil, nil
+	}, repl.Doc{
+		Brief: "displays hello",
+		Detailed: `
+			This displays the message 'hello' to the terminal.
+			It then terminates.
+		`,
+	})
+
 	for {
 		line, err := rl.Readline()
 		if err != nil { // io.EOF
 			break
 		}
 
-		if err := ucl.EvalAndDisplay(ctx, inst, line); err != nil {
+		if err := instRepl.EvalAndDisplay(ctx, line); err != nil {
 			log.Printf("%T: %v", err, err)
 		}
 	}