clarify, that deb.d.o is only used if SUITE is not a stable release

mmdebstrap

@@ -6276,24 +6276,24 @@ dependencies and is thus able to use more than one mirror and resolve more
 complex dependencies. See section B<OPERATION> for an overview of how
 B<mmdebstrap> works internally.
 
-If no I<MIRROR> option is provided, L<http://deb.debian.org/debian> is used.
-If I<SUITE> is a stable release name and no I<MIRROR> is specified, then
-mirrors for updates and security are automatically added. If a I<MIRROR>
-option starts with "deb " or "deb-src " then it is used as a one-line-style
-format entry for apt's sources.list inside the chroot.  If a I<MIRROR> option
-contains a "://" then it is interpreted as a mirror URI and the apt line
-inside the chroot is assembled as "deb [arch=A] B C D" where A is the host's
-native architecture, B is the I<MIRROR>, C is the given I<SUITE> and D is the
-components given via B<--components> (defaults to "main"). If a I<MIRROR>
-option happens to be an existing file, then its contents are pasted into the
-chroot's sources.list.  This can be used to supply a deb822 style
-sources.list. If I<MIRROR> is C<-> then standard input is pasted into the
-chroot's sources.list.  More than one mirror can be specified and are appended
-to the chroot's sources.list in the given order. If you specify a https or tor
-I<MIRROR> and you want the chroot to be able to update itself, don't forget to
-also install the ca-certificates package, the apt-transport-https package for
-apt versions less than 1.5 and/or the apt-transport-tor package using the
-B<--include> option, as necessary.
+If no I<MIRROR> option is provided and I<SUITE> is not a stable release name,
+L<http://deb.debian.org/debian> is used.  If I<SUITE> is a stable release name
+and no I<MIRROR> is specified, then mirrors for updates and security are
+automatically added. If a I<MIRROR> option starts with "deb " or "deb-src "
+then it is used as a one-line-style format entry for apt's sources.list inside
+the chroot.  If a I<MIRROR> option contains a "://" then it is interpreted as a
+mirror URI and the apt line inside the chroot is assembled as "deb [arch=A] B C
+D" where A is the host's native architecture, B is the I<MIRROR>, C is the
+given I<SUITE> and D is the components given via B<--components> (defaults to
+"main"). If a I<MIRROR> option happens to be an existing file, then its
+contents are pasted into the chroot's sources.list.  This can be used to supply
+a deb822 style sources.list. If I<MIRROR> is C<-> then standard input is pasted
+into the chroot's sources.list.  More than one mirror can be specified and are
+appended to the chroot's sources.list in the given order. If you specify a
+https or tor I<MIRROR> and you want the chroot to be able to update itself,
+don't forget to also install the ca-certificates package, the
+apt-transport-https package for apt versions less than 1.5 and/or the
+apt-transport-tor package using the B<--include> option, as necessary.
 
 The optional I<TARGET> argument can either be the path to a directory, the path
 to a tarball filename, the path to a squashfs image, the path to an ext2 image,