Clarify convertClassIf (modelica#2533)

Clarify literal values for convertClassIf (string and enumeration), and that Integer and Boolean is also allosed.
Closes modelica#2451

chapters/annotations.tex

@@ -1566,6 +1566,12 @@ \subsubsection{Conversion rules}\doublelabel{conversion-rules}
 These are considered before \lstinline!convertClass! and \lstinline!convertMessage! for the same
 \lstinline!OldClass!.
 
+The old element should be of a \lstinline!Boolean!, \lstinline!Integer!, \lstinline!String!, or enumeration
+type and the match is based on the literal value of the modifier.
+For string elements the value argument to \lstinline!convertClassIf! shall be up-quoted, e.g. \lstinline!"\"My String\""!,
+and for enumeration literals only the enumeration literal part of the old value matters, e.g., \lstinline!red!
+for \lstinline!"Colors.red"!.
+
 \paragraph*{convertElement("OldClass", "OldName", "NewName")}\doublelabel{convertelementoldclassoldnamenewname}
 
 In \lstinline!OldClass! convert element \lstinline!OldName! to \lstinline!NewName!.