Don't try to build the app when using only the -h or --help flags…

… on the `run` command (#344)

* Don't try to build the app when using the `-h` flag on the `run` command

Fixes #341

* Improve legibility by using guard instead of if statement

Sources/VaporToolbox/Run.swift

@@ -3,7 +3,7 @@ import Foundation
 
 // Generates an Xcode project
 struct Run: AnyCommand {
-    let help = "Runs an app from the console."
+    let help = "Runs an app from the console.\nEquivalent to `swift run --enable-test-discovery Run`."
 
     func run(using context: inout CommandContext) throws {
         var extraArguments: [String] = []
@@ -14,6 +14,11 @@ struct Run: AnyCommand {
     }
 
     func outputHelp(using context: inout CommandContext) {
+        guard context.input.arguments.count > 1 else {
+            context.console.output("\(self.help)")
+            return
+        }
+
         do {
             context.input.arguments.append("--help")
             try self.run(using: &context)