Delete plugins readme files (#1886)

[jz5]

✨ What kind of change does this PR introduce? (Bug fix, feature, docs update...)

Update docs (READMEs). Fix #1886

[Cheesebaron]

Excellent, have you made sure that details from the readme's are not missing from the docs?

[jz5]

Yes. All links are correct.

[Cheesebaron]

I am not talking about the links. But the contents of the pages the links point to.

[martijn00]

Why don't we remove all the readme files, because it should all be on the website anyways.

[jz5]

The plugins docs on mvvmcross.com are newer than readmes. And the docs contain the contents of readmes.
But except location.md. I noticed the content of location.md is old. I copied the content from readme to location.md.

[jz5]

Delete readmes?

[martijn00]

Yes, i was thinking if we just delete all the Readme.mdfiles in the plugin folders we don't need to link anymore. We already have a link to the website and documentation on the readme.md in the root folder.

[jz5]

I changed the commits to delete.

[martijn00]

Please rebase so we can merge your pr.

[jz5]

OK.
Plugins readmes had typos (#1911). But plugins documents on mvvmcross.com have no typos. (already have fixed).