man-pages.7: ffix: remove unneeded .ad tags

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man7/man-pages.7

@@ -597,7 +597,6 @@ and
 .SS Preferred terms
 The following table lists some preferred terms to use in man pages,
 mainly to ensure consistency across pages.
-.ad l
 .TS
 l l l
 ---
@@ -651,7 +650,6 @@ user space	userspace
 username	user name
 zeros	zeroes
 .TE
-.ad
 .PP
 See also the discussion
 .IR "Hyphenation of attributive compounds"
@@ -660,7 +658,6 @@ below.
 The following table lists some terms to avoid using in man pages,
 along with some suggested alternatives,
 mainly to ensure consistency across pages.
-.ad l
 .TS
 l l l
 ---
@@ -687,7 +684,6 @@ tty	terminal
 Unices	UNIX systems
 Unixes	UNIX systems
 .TE
-.ad
 .SS Trademarks
 Use the correct spelling and case for trademarks.
 The following is a list of the correct spellings of various