Add submission.yaml for example submission metadata

spec/2023-07-draft.md

@@ -554,10 +554,19 @@ The possible subdirectories are:
 | run_time_error                                    | Crashes for some test case. May output wrong answers or be too slow for other test cases.                          | Very rarely useful.
 
 Every file or directory in these directories represents a separate solution.
-Same requirements as for submissions with regards to filenames.
 It is mandatory to provide at least one accepted solution.
 
-Submissions must read input data from standard input, and write output to standard output.
+Metadata about the example submissions are provided in a UTF-8 encoded YAML file named `submissions.yaml` placed directly in the `submissions/` directory.
+The top level keys in `submissions.yaml` are globs matching example submissions.
+For example, `accepted/*` would match any submission in the `submissions/accepted/` directory.
+
+Each glob maps to a map with keys as defined below specifying metadata for all submissions that is matched by the glob.
+
+| Key        | Type                          | Default                                                               | Comment
+| ---------- | ----------------------------- | --------------------------------------------------------------------- | -------
+| language   | String                        | As determined by file endings given in the [language list](#programs) |
+| entrypoint | String                        | As specified in the [language list](#programs)                        |
+| authors    | Person or sequence of persons |                                                                       | Author(s) of submission(s)
 
 ## Input Validators