[folks] HACKING: Update documentation for running single tests

[Philip Withnall <pwithnall src gnome org>]

commit 70adbe45ba9ba859ea083e95478770d55ba82b07
Author: Philip Withnall <philip tecnocode co uk>
Date:   Thu Jan 3 11:18:35 2013 +0000

    HACKING: Update documentation for running single tests

 HACKING |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/HACKING b/HACKING
index 51a66b6..c031cfd 100644
--- a/HACKING
+++ b/HACKING
@@ -146,10 +146,13 @@ hooks for each test. Simply run:
 Then use gdb as normal.
 
 To run a single test:
-  make check TESTS=avatar-cache
+        make -C tests/<dir> check TESTS=<test name>
 
 To run a single test with debugging output:
-  make check TESTS=avatar-cache CHECK_VERBOSE=1
+        make -C tests/<dir> check TESTS=<test name> CHECK_VERBOSE=1
+
+If a test needs to be run through Valgrind for memory debugging, use:
+        make -C tests/<dir> check TESTS=<test name> FOLKS_TEST_VALGRIND=1
 
 Profiling folks
 ===============