fix translation

Author: Vladimir Kotal

intro.tex

@@ -1182,7 +1182,7 @@
 \item defining a macro on a command line: \\
 \hspace*{5em}\texttt{make \emph{target} \emph{name}=\emph{string}}
 \item macro invocation: \\
-\hspace*{5em}\texttt{\$\emph{name}} (pouze jednoznakové
+\hspace*{5em}\texttt{\$\emph{name}} (only one character
 \texttt{\emph{name}}), \\
 \hspace*{5em}\texttt{\$\{\emph{name}\}} or \texttt{\$(\emph{name})}
 \item environment variables are accessible as macros (eg. \texttt{\$\{EDITOR\}})