Start writing run command tutorial

doc/tutorial/run.md

@@ -1 +1,57 @@
 # Tutorial: provide run commands
+
+Now that your language is installed you need to tell Riju how to run
+it. Here's an example for Dart:
+
+```yaml
+main: "main.dart"
+template: |
+  void main() {
+    print('Hello, world!');
+  }
+
+run: |
+  dart main.dart
+```
+
+Note:
+
+* The contents of `template` are put into the `main` filename, and
+  `run` is expected to run that file.
+* The `main` filename should follow existing conventions for your
+  language, typically `main.foo` where `foo` is a standard file
+  extension. If there's no standard file extension you can pick a
+  reasonable-sounding one, like `main.beatnik` for Beatnik. You can
+  use subdirectories (e.g. `src/main.foo`) if needed, but this is
+  pretty rare.
+* The `template` code should print exactly the text `Hello, world!`
+  with a trailing newline to stdout, or as close to that as possible.
+
+## Compiled languages
+
+If your language has a separate compilation step that produces a
+binary or other intermediate artifact, you can add a separate
+`compile` command; for example:
+
+```yaml
+main: "Main.java"
+template: |
+  public class Main {
+      public static void main(String[] args) {
+          System.out.println("Hello, world!");
+      }
+  }
+
+compile: |
+  javac Main.java
+run: |
+  java Main
+```
+
+There is no hard requirement on the names of intermediate files. In
+the case of Java, the intermediate file is named `Main.class`, with
+the `java` command appending the `.class` part implicitly.
+
+## Languages with REPLs
+
+## Variable scope