Spelling fix

Doc/lib/libdatetime.tex

@@ -52,7 +52,7 @@ The \module{datetime} module exports the following constants:
 \end{datadesc}
 
 \begin{seealso}
-  \seemodule{calendar}{General calandar related functions.}
+  \seemodule{calendar}{General calendar related functions.}
   \seemodule{time}{Time access and conversions.}
 \end{seealso}