46240: Make the expansion of manref()() in ztexi.yo match its expansion in zman.yo.

The difference was mostly harmless in the common case "(see manref(foo)(42))",
which expanded to "(see man page foo(42))" under ztexi.yo, but in other
contexts the ztexi.yo expansion was was nonsensical; for example:

    "the BSD manref(echo)(1) command"

    "the string returned by the manref(getlogin)(3) system call"

    "advisory file locking (via the manref(fcntl)(2) system call)"

    "this is the exact opposite from manref(ls)(1),"

While there, copyedit some uses of manref()().

Doc/Zsh/params.yo

@@ -731,7 +731,7 @@ explicitly set locally.
 )
 vindex(ERRNO)
 item(tt(ERRNO) <S>)(
-The value of errno (see manref(errno)(3))
+The value of tt(errno) (see manref(errno)(3))
 as set by the most recently failed system call.
 This value is system dependent and is intended for debugging
 purposes.  It is also useful with the tt(zsh/system) module which