Add missing period at end of last sentence in abstract (#2677)

chapters/abstract.tex

@@ -31,8 +31,7 @@
 utilized to enable efficient handling of large models having more than
 one hundred thousand equations. Modelica is suited and used for
 hardware-in-the-loop simulations and for embedded control systems. More
-information is available at
-\url{https://www.modelica.org}
+information is available at \url{https://www.modelica.org}.
 \end{abstract}
 
 \hypersetup{pageanchor=true}