Further tidy on Android instructions README.md (#7077)

* Further tidy on Android instructions README.md

Fixed some logic when following readme direction

* Clean up redundent information

A new user arriving will see simple directions on llama.cpp homepage

* corrected puncuation

Period after cmake, colon after termux

* re-word for clarity

method seems to be more correct, instead of alternative in this context

* Organized required packages per build type

building llama.cpp with NDK on a pc doesn't require installing clang, cmake, git, or wget in termux.

* README.md

corrected title

* fix trailing whitespace