chore(docs): add documentation for exp CLI commands (#20019)

Updates task documentation with experimental CLI.
~Generated by Claude using `--help` output.~

Should be merged alongside https://github.com/coder/coder/pull/20020

cli/exp_task_create.go

@@ -29,6 +29,28 @@ func (r *RootCmd) taskCreate() *serpent.Command {
 	cmd := &serpent.Command{
 		Use:   "create [input]",
 		Short: "Create an experimental task",
+		Long: FormatExamples(
+			Example{
+				Description: "Create a task with direct input",
+				Command:     "coder exp task create \"Add authentication to the user service\"",
+			},
+			Example{
+				Description: "Create a task with stdin input",
+				Command:     "echo \"Add authentication to the user service\" | coder exp task create",
+			},
+			Example{
+				Description: "Create a task with a specific name",
+				Command:     "coder exp task create --name task1 \"Add authentication to the user service\"",
+			},
+			Example{
+				Description: "Create a task from a specific template / preset",
+				Command:     "coder exp task create --template backend-dev --preset \"My Preset\" \"Add authentication to the user service\"",
+			},
+			Example{
+				Description: "Create a task for another user (requires appropriate permissions)",
+				Command:     "coder exp task create --owner user@example.com \"Add authentication to the user service\"",
+			},
+		),
 		Middleware: serpent.Chain(
 			serpent.RequireRangeArgs(0, 1),
 		),