Add optional parameter to 'avb verify' sub-command, so that user is able
to specify which slot to use, in case when user's partitions are
slotted. If that parameter is omitted, the behavior of 'avb verify' will
be the same as before, so user API is content.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Igor Opaniuk <igor.opaniuk@gmail.com>
Acked-by: Igor Opaniuk <igor.opaniuk@gmail.com>

As per [1], there is no such fastboot variable as "bootloader-version".
Only "version-bootloader" is supported. Let's reflect this and not
confuse users further.

[1] https://android.googlesource.com/platform/system/core/+/refs/tags/android-q-preview-4/fastboot/README.md

Fixes: 3aab70afc531d1 ("usb/gadget: add the fastboot gadget")
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Eugeniu Rosca <erosca@de.adit-jv.com>

Add a short documentation for A/B enablement and 'ab_select' command
usage.

Signed-off-by: Ruslan Trofymenko <ruslan.trofymenko@linaro.org>
Signed-off-by: Igor Opaniuk <igor.opaniuk@gmail.com>
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Alistair Strachan <astrachan@google.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>

Rename:
 - doc/{README.avb2 => android/avb2.txt}
 - doc/{README.android-fastboot => android/fastboot.txt}

Add a new file documenting the 'bcb' command:
 - doc/android/bcb.txt

The new directory structure has been reviewed by Simon in
https://patchwork.ozlabs.org/patch/1101107/#2176031 .

Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
Reviewed-by: Simon Glass <sjg@chromium.org>