[java-atk-wrapper] document extended JAW_DEBUG values

[Samuel Thibault <sthibaul src gnome org>]

commit e91ae96bd4236ffe09882a1dd0dedb14d00967bf
Author: Samuel Thibault <samuel thibault ens-lyon org>
Date:   Sun Jul 28 11:26:28 2019 +0200

    document extended JAW_DEBUG values

 HACKING | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)
---
diff --git a/HACKING b/HACKING
index 465dda1..fabbae9 100644
--- a/HACKING
+++ b/HACKING
@@ -54,18 +54,20 @@ Conventions for Writing Java ATK Wrapper Code
 ---------------------------------------------
 
 Spaces instead of tabs.
-Two spaces per indent.
+Four spaces per indent.
 
 JNI warning and error messages are in the form:
 
-  if (jaw_debug)
-    g_warning("method calling instance: instance == NULL");
+  JAW_DEBUG_I("method calling instance: instance == NULL");
 
-These statements will only print if the environment variable JAW_DEBUG is set to 1. To use this
-setting type the following into the terminal or set it in ~/.bashrc:
+These statements will only be emitted to jaw_log_file.txt if the environment
+variable JAW_DEBUG is set to 1. To use this setting type the following into the
+terminal or set it in ~/.bashrc:
 
   export JAW_DEBUG=1
 
+More JAW_DEBUG level values are available (2: JAW_DEBUG_JNI, 3: JAW_DEBUG_C, 4: JAW_DEBUG_ALL)
+
 Other Things to Keep in Mind
 ----------------------------