Update docstring in rezconfig.py to escape backslash

Signed-off-by: Thorsten Kaufmann <[email protected]>

Author: instinct-vfx

src/rez/rezconfig.py

@@ -38,7 +38,8 @@
 
 Paths should use the path separator appropriate for the operating system
 (based on Python's os.path.sep).  So for Linux paths, / should be used. On
-Windows \ (unescaped) should be used.
+Windows \\ (unescaped! A change in python 3.12 does not allow single backslashes
+in docstrings. Sorry.) should be used.
 
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 attention to the comment formatting and follow the existing style closely.