fixups: typos and grammar (support.tex)

Author: notadragon

source/support.tex

@@ -4492,7 +4492,7 @@
 \returns
 \keyword{true} if the evaluation semantic is
 a terminating semantic\iref{basic.contract.eval};
-otherwise \tcode{false}.
+otherwise, \tcode{false}.
 
 \end{itemdescr}
 
@@ -4516,7 +4516,7 @@
 \begin{itemdescr}
 \pnum
 \returns
-A \tcode{source_location}object
+A \tcode{source_location} object
 with
 \impldef{the contents provided in the \tcode{location} field of \tcode{contract_violation}}
 value.