fix: additional braces in description of key handler .append code

doc/generic/pgf/pgfmanual-en-pgfkeys.tex

@@ -1107,7 +1107,7 @@ \subsubsection{Defining Key Codes}
 
 \begin{handler}{{.append code}|=|\meta{append code}}
     This handler is a shortcut for \meta{key}|/.add code={}{|\meta{append
-    code}|}{}|.
+    code}|}|.
 \end{handler}
 
 
@@ -1249,7 +1249,7 @@ \subsubsection{Defining Value-, Macro-, If- and Choice-Keys}
     and, thus, |\pgfkeysnovalue| will be stored in |/my key|.
 
     To retrieve the value stored in a key, the handler |/.get| is used.
-    
+
     \medskip
     \emph{Remark:} A key can both store a value and execute commands%
     \footnote{This behavior was partially changed in \pgfname{} 3.1.6 and then