Documentation: Spell vboot all lowercase

Update all occurrences of vboot and spell it lowercase.

Change-Id: I432b0db8a3dda43b71844e557a3d89180f25f1c3
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.io>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39799
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

Documentation/security/vboot/index.md

@@ -196,7 +196,7 @@ not into the read/write coreboot file systems in *FW_MAIN_A* and *FW_MAIN_B*.
 **VBOOT_ENABLE_CBFS_FALLBACK**  
 
 Normally coreboot will use the active read/write coreboot file system for all
-of it's file access when VBOOT is active and is not in recovery mode.
+of it's file access when vboot is active and is not in recovery mode.
 
 When the `VBOOT_ENABLE_CBFS_FALLBACK` option is enabled the cbfs file system will
 first try to locate a file in the active read/write file system. If the file

Documentation/security/vboot/list_vboot.md

@@ -1,4 +1,4 @@
-# VBOOT enabled devices
+# vboot-enabled devices
 
 ## Emulation
 - QEMU x86 i440fx/piix4 (aka qemu -M pc)

Documentation/security/vboot/measured_boot.md

@@ -120,12 +120,12 @@ PCR-7 are left empty.
 ### PCR-0
 _Hash:_ SHA1
 
-_Description:_ Google VBoot GBB flags.
+_Description:_ Google vboot GBB flags.
 
 ### PCR-1
 _Hash:_ SHA1/SHA256
 
-_Description:_ Google VBoot GBB HWID.
+_Description:_ Google vboot GBB HWID.
 
 ### PCR-2
 _Hash:_ SHA1/SHA256