bootstd: Adjust the default bootmeth order

The existing distro scripts check extlinux and scripts before EFI. Adjust
the default ordering to do the same, to avoid breaking existing flows.

Add some documentation, mentioning that this order will likely change in
future.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reported-by: Da Xue <da@libre.computer>
diff --git a/doc/develop/bootstd.rst b/doc/develop/bootstd.rst
index ec31365..c47de27 100644
--- a/doc/develop/bootstd.rst
+++ b/doc/develop/bootstd.rst
@@ -132,6 +132,9 @@
 Controlling ordering
 --------------------
 
+By default, faster bootdevs (or those which are assumed to be faster) are used
+first, since they are more likely to be able to boot the device quickly.
+
 Several options are available to control the ordering of boot scanning:
 
 
@@ -151,6 +154,10 @@
 bootmeths
 ~~~~~~~~~
 
+By default bootmeths are checked in name order. Use `bootmeth list` to see the
+ordering. Note that the `extlinux` and `script` bootmeth is first, to preserve the behaviour
+used by the old distro scripts.
+
 This environment variable can be used to control the list of bootmeths used and
 their ordering for example::
 
@@ -164,7 +171,6 @@
 The :ref:`usage/cmd/bootmeth:bootmeth command` (`bootmeth order`) operates in
 the same way as setting this variable.
 
-
 Bootdev uclass
 --------------