twrpme: Update installation instructions for A only & AB devices

*Updated links to platform-tools
*Moved current AB installation method as old by renaming the include & Added new method introduced in https://github.com/TeamWin/android_bootable_recovery/commit/53796e73334ac9d87d4cb5a355fc8c1d205104f6
*Misc updates

Change-Id: I10c695c9e3faab205ee206dc4e261cbc07bcffc8
4 files changed