[m-rev.] diff: fix incorrect documentation for string.format

[Julien Fischer]

Fix incorrect documentation for string.format.

library/string.m:
     The o, x and X conversion specifiers all produce an unsigned
     representation *not* a signed one.

Julien.

diff --git a/library/string.m b/library/string.m
index 8082c07..251dfed 100644
--- a/library/string.m
+++ b/library/string.m
@@ -1345,8 +1345,8 @@
      %
      % d     int     signed integer
      % i     int     signed integer
-    % o     int     signed octal        with '0' prefix
-    % x,X   int     signed hex          with '0x', '0X' prefix
+    % o     int     unsigned octal      with '0' prefix
+    % x,X   int     unsigned hex        with '0x', '0X' prefix
      % u     int     unsigned integer
      % c     char    character
      % s     string  string