When invoked from inside `texdoc', `%' isn't a comment character, and
`\alpha', rather than `\alph', isn't allowed outside maths mode.
Remove these lines, because they're not contributing anything very
useful.
\end{center}
-%\renewcommand{\theenumi}{\alpha{enumi}}
\begin{enumerate}
\addtocounter{enumi}{-1}
\end{center}
-%\renewcommand{\theenumi}{\alpha{enumi}}
\begin{enumerate}
\addtocounter{enumi}{-1}
\end{center}
-%\renewcommand{\theenumi}{\alpha{enumi}}
\begin{enumerate}
\addtocounter{enumi}{-1}