new-style documentation for most commands

libexec/rbenv-help

@@ -1,4 +1,16 @@
 #!/usr/bin/env bash
+#
+# Summary: Display help for a command
+#
+# Usage: rbenv help [--usage] COMMAND
+#
+# Parses and displays help contents from a command's source file.
+#
+# A command is considered documented if it starts with a comment block that has
+# at least one of the following sections: `Summary' and `Usage'. Usage
+# instructions can span multiple lines as long as subsequent lines are indented.
+# Everything else in the comment is considered to be regular help contents.
+
 set -e
 [ -n "$RBENV_DEBUG" ] && set -x