manual: minor fix in patch-policy.txt

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

docs/manual/patch-policy.txt

@@ -34,12 +34,18 @@ Most patches are provided within Buildroot, in the package
 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
 ~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -56,8 +62,12 @@ 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.