[fs.class.path] Ensure interword spacing inside sentence. (#4083)

Author: Eelis

source/iostreams.tex

@@ -11702,7 +11702,7 @@
 an implied starting location. The elements of a path that determine if it is
 relative are operating system dependent.
 \begin{note}
-Pathnames ``.'' and ``..'' are relative paths.
+Pathnames ``.''\ and ``..''\ are relative paths.
 \end{note}
 
 \pnum