Fix a typo
diff --git a/Doc/lib/libos.tex b/Doc/lib/libos.tex
index 42acc35..c93c835 100644
--- a/Doc/lib/libos.tex
+++ b/Doc/lib/libos.tex
@@ -918,7 +918,7 @@
time stamps represented as floats. Whether they will actually observe
non-zero fractions depends on the system.
-Future Python releases will change the default of this settings;
+Future Python releases will change the default of this setting;
applications that cannot deal with floating point time stamps can then
use this function to turn the feature off.