manual: minor fix in patch-policy.txt

directory; these typically aim to fix cross-compilation, libc support,

or other such issues.

These patch files should be named +<packagename>-<description>.patch+.

These patch files should be named +<packagename>-<number>-<description>.patch+.

A +series+ file, as used by +quilt+, may also be added in the

package directory. In that case, the +series+ file defines the patch

application order.

.Notes

- The patch files coming with Buildroot should not contain any package version

reference in their filename.

- The field +<number>+ in the patch file name refers to the 'apply order'.

How patches are applied

~~~~~~~~~~~~~~~~~~~~~~~

* If a +series+ file exists in the package directory, then patches are

  applied according to the +series+ file;

+

* Otherwise, patch files matching `<packagename>-*.patch` are applied

  following the +ls+ command order.

* Otherwise, patch files matching +<packagename>-*.patch+

  are applied in alphabetical order.

  So, to ensure they are applied in the right order, it is hightly

  recommended to named the patch files like this:

  +<packagename>-<number>-<description>.patch+, where +<number>+

  refers to the 'apply order'.

. Run the +<packagename>_POST_PATCH_HOOKS+ commands if defined.