Update main.tex
Rephrased according to suggestion
@@ -1035,7 +1035,7 @@ If you would like to contribute to \ccl or contact the developers, please do so
\section{Citing \ccl}
\label{sec:cite}
-If you use \ccl in your work, please provide a link to the repository and cite it as LSST DESC (in preparation). \ccl has a built-in version of {\tt CLASS} for convenience, thus \ccl users must cite the {\tt CLASS} paper: {\it CLASS II: Approximation schemes}, D. Blas, J. Lesgourgues, T. Tram, arXiv:1104.2933, JCAP 1107 (2011) 034.
+If you use \ccl in your work, please provide a link to the repository and cite it as LSST DESC (in preparation). For free use of the {\tt CLASS} library, the {\tt CLASS} developers require that the {\tt CLASS} paper be cited: {\it CLASS II: Approximation schemes}, D. Blas, J. Lesgourgues, T. Tram, arXiv:1104.2933, JCAP 1107 (2011) 034. The {\tt CLASS} repository can be found in \url{http://class-code.net}.
\section{License}
\label{sec:license}
