Fix typos layer and geom_text docs

[collinberke]

I was reading the geom_text() docs and came across these minor typos. Feel free to reject or modify any change that goes against the original intent of what was originally written.

Thanks for maintaining this awesome package!

[collinberke]

I just realized I didn't include all the files from devtools::document(), since many functions use @inheritParams layer. If I need to back this out and resubmit, let me know.

[teunbrand]

Hi there, thanks for the PR! It would be nice to regenerate all the relevant docs. I don't think there is a need to back out / resubmit. You could just add a second commit to the same branch and push again, at which point this PR would update with the latest changes.

[collinberke]

@teunbrand , I just added the missing files in 6b557c4.

[thomasp85]

LGTM

[thomasp85]

Thank you!