Resolve "Typo in appendix's circular buffer example"

Closes #2 (closed)

examples/cirbuf.tex

@@ -30,7 +30,7 @@
 \end{itemize}
 
 \subsection{Code}
-Let $\ptwi = 0, \ptri = 0, \ptbuf = 0$.
+Let $\ptwi = 0, \ptri = 1, \ptbuf = 2$.
 
 \begin{hproofenv}
   \cdline{\enewb() \eqdef}~\\