Fix header rendering in Sphinx

Before it rendered somewhat like this at
https://salt.readthedocs.org/en/latest/ref/states/all/index.html:

```
dockerio<tab>Management of dockers ===================== ..
```
Fix header rendering in Sphinx

Before it rendered somewhat like this at
https://salt.readthedocs.org/en/latest/ref/states/all/index.html:

```
saltmod<tab>The Salt state is used to control the salt command interface. This state is<empty>
```
Move import of salt.utils.
Remove punctuation in headers.

The display in the [states
index](https://salt.readthedocs.org/en/latest/ref/states/all/index.html)
was not consistent. Many state modules did end in a dot, but most
didn't.
Merge pull request #8722 from holmboe/doc-style-fixes

Doc style fixes