Tidy Android Instructions README.md (#7016)

Tidy Android Instructions README.md (#7016)

* Tidy Android Instructions README.md

Remove CLBlast instructions(outdated), added OpenBlas.

* don't assume git is installed

Added apt install git, so that git clone works

* removed OpenBlas

Linked to Linux build instructions

* fix typo

Remove word "run"

* correct style

Co-authored-by: slaren <redacted>
* correct grammar

Co-authored-by: slaren <redacted>
* delete reference to Android API

* remove Fdroid reference, link directly to Termux

Fdroid is not required

Co-authored-by: slaren <redacted>
* Update README.md

Co-authored-by: slaren <redacted>
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Co-authored-by: slaren <redacted>