Update functions.tex

Clarify multiple license files and simplify reference.

chapters/functions.tex

@@ -2399,10 +2399,10 @@ \subsection{Annotations for External Functions}\label{annotations-for-external-l
   The preceding one is the default and need not be specified; but another location could be specified by using an URI name for the source directory, see \cref{external-resources}.
   It is not specified how they are built.
 \item
-  The {\lstinline!annotation(License="modelica:/ModelicaLibraryName/Resources/Licenses/MyLicense.txt")!}\annotationindex{License}, gives the license files for the function.
+  The {\lstinline!annotation(License="modelica:/ModelicaLibraryName/Resources/Licenses/MyLicense.txt")!}\annotationindex{License}, gives the license file for the function.
   The license files are human-readable files containing the license conditions.
-  Top-level classes may also contain this annotation (with similar contents), see \cref{license-texts}.
-  When generating a distributable version for a translated model the license files for used functions and top-level classes should be included.
+  If the annotation specifies an array of license files the conditions in all of them must be satisfied (i.e., it is not intended for dual-licensing).
+  It is analogous to the \lstinline!License!-annotation for a top-level class, see \cref{license-texts}.
 \end{itemize}
 
 The \filename{win32} or \filename{win64} directories may contain \filename{gcc47}, \filename{vs2010}, \filename{vs2012}