Fix a variable name in winreg docs.
(backport from rev. 56091)
diff --git a/Doc/lib/libwinreg.tex b/Doc/lib/libwinreg.tex
index d1e23da..184b750 100644
--- a/Doc/lib/libwinreg.tex
+++ b/Doc/lib/libwinreg.tex
@@ -321,7 +321,7 @@
\var{key} is an already open key, or one of the predefined
\constant{HKEY_*} constants.
- \var{sub_key} is a string that names the subkey with which the
+ \var{value_name} is a string that names the subkey with which the
value is associated.
\var{type} is an integer that specifies the type of the data.