Fix some typos.

Add an index entry.

Doc/lib/libsched.tex

@@ -7,7 +7,7 @@
 \modulesynopsis{General purpose event scheduler.}
 
 The \module{sched} module defines a class which implements a general
-purpose event scheduler:
+purpose event scheduler:\index{event scheduling}
 
 \begin{classdesc}{scheduler}{timefunc, delayfunc}
 The \class{scheduler} class defines a generic interface to scheduling
@@ -43,9 +43,9 @@ From print_time 930343700.273
 \end{verbatim}
 
 
-\subsection{Schedule Objects \label{schedule-objects}}
+\subsection{Scheduler Objects \label{scheduler-objects}}
 
-\class{schdule} instances have the following methods:
+\class{scheduler} instances have the following methods:
 
 \begin{methoddesc}{enterabs}{time, priority, action, argument}
 Schedule a new event. The \var{time} argument should be a numeric type
@@ -74,7 +74,7 @@ currently in the queue, this method will raise a
 \end{methoddesc}
 
 \begin{methoddesc}{empty}{}
-Check whether there are no scheduled events.
+Return true if the event queue is empty.
 \end{methoddesc}
 
 \begin{methoddesc}{run}{}