Fixed typos and metrics name

[chebyrash]

I have fixed a couple of typos in comments, READMEs and variable names. However, there was typo in a the following line of code - ...WithLabelValues(h.protocol, "unsibscribe")... where "unsubscribe" was incorrectly spelled. This can be a problem if metrics label names are incorrectly spelled, so it might be a good idea to put those names in a separate const ( ... ) space.

[FZambia]

Thanks! I've also pushed a fix for CI to not try login to docker on pull requests in fa01b4b.

[FZambia]

@chebyrash also I returned several lines you deleted for some reason: e864024

[chebyrash]

@FZambia sorry, I deleted the wrong lines. I wanted to fix it like below
Golint shows that code from e864024

if err = addExtensionConventionForRollups(buf, mf, m); err != nil {
		return err
	}
return nil

Can be rewritten because if ...; err != nil check, just return error instead.

return addExtensionConventionForRollups(buf, mf, m);

[FZambia]

Yeah, right – if you have time please send another pr with this fix, if not – I'll fix it myself soon.