bug#34756: 26.1.92; Minor typos across manuals

[Eli Zaretskii]

> From: "Basil L. Contovounesios" <contovob@tcd.ie>
> Date: Tue, 05 Mar 2019 08:41:21 +0000
> 
> Are the three attached patches acceptable for the emacs-26 branch?

Documentation changes should always go to the release branch, unless
they document features only available on master.

> If so, should I add this bug number to all or none of them?

It's okay to push all of them under the same bug number, and even in a
single commit.  There's no need to distinguish between changes that
correct typos, they are all "alike" for all practical purposes.

Thanks.