Document updates for 23.02

* Remove the PerformanceChart. png file which is no more used in the Readme
* Update release version for pre-built binaries in readme
* Remove link to outdated guide in readme
* Update example release branch in Android NDK md file

Signed-off-by: Nikhil Raj <nikhil.raj@arm.com>
Change-Id: I8f5cac684f9fa1c9ec5d2ba2286dea5dd47136ca