Add some detail to signal docstring

Author: sogaiu

src/core/corelib.c

@@ -700,7 +700,15 @@ JANET_CORE_FN(janet_core_is_lengthable,
 
 JANET_CORE_FN(janet_core_signal,
               "(signal what x)",
-              "Raise a signal with payload x. ") {
+              "Raise a signal with payload x. `what` can be an integer\n"
+              "from 0 through 7 indicating user(0-7), or one of:\n\n"
+              "* :ok\n"
+              "* :error\n"
+              "* :debug\n"
+              "* :yield\n"
+              "* :user(0-7)\n"
+              "* :interrupt\n"
+              "* :await") {
     janet_arity(argc, 1, 2);
     Janet payload = argc == 2 ? argv[1] : janet_wrap_nil();
     if (janet_checkint(argv[0])) {

src/core/util.c

@@ -79,6 +79,7 @@ const char *const janet_type_names[16] = {
     "pointer"
 };
 
+/* Docstring for signal lists these */
 const char *const janet_signal_names[14] = {
     "ok",
     "error",
@@ -96,6 +97,7 @@ const char *const janet_signal_names[14] = {
     "await"
 };
 
+/* Docstring for fiber/status lists these */
 const char *const janet_status_names[16] = {
     "dead",
     "error",