[ostream.formatted.reqmts] Fix incomplete sentence in footnote.

Author: zygoloid

source/iostreams.tex

@@ -6148,7 +6148,7 @@
 which can throw an exception.
 If an exception is thrown during output, then
 \tcode{ios_base::badbit}
-is turned on\footnote{without causing an
+is turned on\footnote{This is done without causing an
 \tcode{ios_base::failure}
 to be thrown.}
 in
@@ -6552,8 +6552,7 @@
 to generate the requested output.
 If an exception is thrown during output, then
 \tcode{ios_base::badbit}
-% .Fs new
-is turned on\footnote{without causing an
+is turned on\footnote{This is done without causing an
 \tcode{ios_base::failure}
 to be thrown.}
 in