Merge ~bettyl/plainbox-provider-checkbox:modify-check-fde-tpm into plainbox-provider-checkbox:master

[Betty Lin]

[Kristin Chuang (kristinchuang)]

A few typos and a suggestion, please see inline comments :)

review: Needs Fixing

[Betty Lin (bettyl)]

＠Kristin, please review again, thanks!

review: Needs Resubmitting

[Kristin Chuang (kristinchuang)]

Thanks Betty!

+1, looks good to me now.

I've also ran `checkbox-cli run com.canonical.certification::disk/encryption/check-fde-tpm` and confirmed that the modified test can be launched, displayed and run w/o issues.

review: Approve

diff --git a/units/disk/encryption.pxu b/units/disk/encryption.pxu
index b805a37..d4c5df8 100644
--- a/units/disk/encryption.pxu
+++ b/units/disk/encryption.pxu
@@ -37,12 +37,14 @@ _purpose:
  BIOS), the device won't be able to get the master key and decrypt its data
  partition.
 _steps:
+ NOTE!!!! YOU'LL HAVE TO RE-INSTALL THE IMAGE AFTER THIS TEST
  1. Install the image and make sure it boots and you can log in.
- 2. Turn the device off and upgrade/downgrade the BIOS or modify Secure Boot state
- 3. Make sure the BIOS is set up properly (e.g. TPM enabled, UEFI boot mode)
- 4. Start the device
+ 2. Make sure the BIOS is set up properly (e.g. TPM enabled, UEFI boot mode)
+ 3. Based on your project's situation, choose one of the following methods to clean TPM:
+    a. Turn the device off and upgrade/downgrade the BIOS or modify Secure Boot state
+    b. Clean TPM via BIOS menu
+    c. Install checkbox, execute "checkbox-[project name].checkbox-cli run com.canonical.certification::tpm2.0_3.0.4/tpm2_takeownership"
+ 4. Start or reboot the device
 _verification:
  Mark this test as "Passed" if the device cannot boot anymore.
- Note: You must flash the BIOS back to the latest version, re-enable Secure Boot
- and re-install the image afterwards.