docs: fix typo in git-config --default

Signed-off-by: Brian Lyles <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: zivarah

Documentation/git-config.txt

@@ -286,7 +286,7 @@ Valid `<type>`'s include:
 
 --default <value>::
   When using `--get`, and the requested variable is not found, behave as if
-  <value> were the value assigned to the that variable.
+  <value> were the value assigned to that variable.
 
 CONFIGURATION
 -------------