posix.py: Add a few comment separator lines to generated pages

Signed-off-by: Michael Kerrisk (man-pages) <mtk.manpages@gmail.com>
diff --git a/posix.py b/posix.py
index e3b77dd..b4bbb0f 100755
--- a/posix.py
+++ b/posix.py
@@ -318,14 +318,16 @@
       "'\\\" et\n"
       ".TH {} \"{}\" 2017 \"IEEE/The Open Group\" \"POSIX Programmer's Manual\"\n"
+      ".\\\"\n"
       ".SH PROLOG\n"
       "This manual page is part of the POSIX Programmer's Manual.\n"
       "The Linux implementation of this interface may differ (consult\n"
       "the corresponding Linux manual page for details of Linux behavior),\n"
       "or the interface may not be implemented on Linux.\n"
-      "\n"
+      ".\\\"\n"
       "".format(NAME, section.upper()))
+      ".\\\"\n"
       ".SH COPYRIGHT\n"
       "Portions of this text are reprinted and reproduced in electronic form\n"
       "from IEEE Std 1003.1-2017, Standard for Information Technology\n"