Replace centering by an environment

More LaTeX idomatic

book/troubleshooting/misc.tex

@@ -357,10 +357,11 @@ protecting your sourdough starter from aerobic mold entering through
 the top.
 
 \begin{figure}[!htb]
-  \centering
+\begin{center}
   \includegraphics[width=0.5\textwidth]{hooch}
   \caption{Hooch building on top of a sourdough starter~\cite{liquid+on+starter}.}%
   \label{fig:hooch}
+\end{center}
 \end{figure}
 
 Simply stir your sourdough starter to homogenize the hooch back
@@ -383,10 +384,11 @@ When tasting acetic acid, the flavor of your bread is often perceived
 as quite strong.
 
 \begin{figure}[!htb]
-  \centering
+\begin{center}
   \includegraphics[width=1.0\textwidth]{ethanol-oxidation}
   \caption{Oxygen is required to create acetic acid~\cite{acetic+acid+production}.}%
   \label{fig:ethanol-oxidation}
+\end{center}
 \end{figure}
 
 This is nothing bad. But if you would like to change