[gcr] README: s/G_DEBUG_MESSAGES/G_MESSAGES_DEBUG

[Daiki Ueno <dueno src gnome org>]

commit 1b872fc354e0f85f7cac607ff477dabd785323c6
Author: Dmitry Eremin-Solenikov <dbaryshkov gmail com>
Date:   Sun Jan 12 23:48:36 2020 +0300

    README: s/G_DEBUG_MESSAGES/G_MESSAGES_DEBUG
    
    Fix my previous mistake with environment variable name.
    
    Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov gmail com>

 README | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/README b/README
index af148d4..09b687b 100644
--- a/README
+++ b/README
@@ -12,20 +12,20 @@ DEBUG TRACING
 The Gcr and Gck libraries contain statements which help debug flow
 and logic. In many cases these help you track down problems.
 
-Use the environment variable G_DEBUG_MESSAGES='all' or G_DEBUG_MESSAGES='xxx'
+Use the environment variable G_MESSAGES_DEBUG='all' or G_MESSAGES_DEBUG='xxx'
 to display either all messages or a specific categories of debug messages. You
 can separate categories in this list with spaces, commas or semicolons. Gcr
 library uses category 'Gcr', while Gck library uses category 'Gck'.
 
 Example to display all debug messages:
 
- $ G_DEBUG_MESSAGES=all gcr-viewer /path/to/certificate.crt
+ $ G_MESSAGES_DEBUG=all gcr-viewer /path/to/certificate.crt
  (gcr-viewer:9418): Gcr-DEBUG: gcr_pkcs11_initialize_async: starting initialize of registered modules
  ...
 
 Example to display debug messages for a specific category:
 
- $ G_DEBUG_MESSAGES="Gcr" gcr-viewer /path/to/certificate.crt
+ $ G_MESSAGES_DEBUG="Gcr" gcr-viewer /path/to/certificate.crt
  (gcr-viewer:9503): Gcr-DEBUG: gcr_pkcs11_initialize_async: starting initialize of registered modules
  ...