Changes to pull_request_template.md for clarity and flow (#5939)

## What are you changing in this pull request and why?
In #5938 I said that the
style guide doc link in the pull request template didn't work and I'd
open a separate pull request. I also couldn't find the style guide on
the docs site under
[contributing](https://docs.getdbt.com/community/contribute), so I was
looking in the wrong place. When I went to edit this file the links
worked. 😆 at myself. I must have copied it wrong the first
time.

However, the template did seem pieced together instead of cohesive, so
I'm here proposing some changes.
* Cut the line break that didn't match the method of the rest of the
document.
* Moved the checklist items that are relevant to al pull requests to the
top of the list. I think this will help contributors understand which
checklist items apply to them. Along with the other changes bulleted
below it should make it so we don't have to read the entire list of
items when submitting each PR in order to make sure we don't skip one.
* Removed the duplicate checklist item about versioning under the
pre-release version checklist items.
* Changed the top line of each optional set of checklist items to be
easy to find and clear about when to use it.
* Changed the phrasing of the statements to make them more like
certifications you've done the required activity. This matches the
dbt-core [pull request
template](https://github.com/dbt-labs/dbt-core/blob/main/.github/pull_request_template.md).

I did not:
* Add a note or reference to a Code of Conduct. I think COCs are vital,
at the same time it may be something you don't want to add to this
particular template to keep the "barriers" to doc contribution low.
* Attempt to cross-link the Docs contribution guidelines with the
dbt-docs style guide.

## Checklist
- [x] Review the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
so my content adheres to these guidelines.
- [x] For [docs
versioning](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#about-versioning),
review how to [version a whole
page](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version)
and [version a block of
content](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-blocks-of-content).
- [x] Add a checklist item for anything that needs to happen before this
PR is merged, such as "needs technical review" or "change base branch."

Co-authored-by: Matt Shaver <[email protected]>

.github/pull_request_template.md

@@ -1,23 +1,22 @@
 ## What are you changing in this pull request and why?
-<!---
-Describe your changes and why you're making them. If related to an open 
-issue or a pull request on dbt Core, then link to them here! 
+<!--
+Describe your changes and why you're making them. If related to an open issue or a pull request on dbt Core or another repository, then link to them here! 
 
 To learn more about the writing conventions used in the dbt Labs docs, see the [Content style guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md).
 -->
 
 ## Checklist
+- [ ] I have reviewed the [Content style guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md) so my content adheres to these guidelines.
+- [ ] The topic I'm writing about is for specific dbt version(s) and I have versioned it according to the [version a whole page](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version) and/or [version a block of content](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-blocks-of-content) guidelines.
+- [ ] I have added checklist item(s) to this list for anything anything that needs to happen before this PR is merged, such as "needs technical review" or "change base branch."
 <!--
-Uncomment when publishing docs for a prerelease version of dbt:
-- [ ] Add versioning components, as described in [Versioning Docs](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-entire-pages)
+PRE-RELEASE VERSION OF dbt (if so, uncomment):
 - [ ] Add a note to the prerelease version [Migration Guide](https://github.com/dbt-labs/docs.getdbt.com/tree/current/website/docs/docs/dbt-versions/core-upgrade)
 -->
-- [ ] Review the [Content style guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md) so my content adheres to these guidelines.
-- [ ] For [docs versioning](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#about-versioning), review how to [version a whole page](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#adding-a-new-version) and [version a block of content](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/single-sourcing-content.md#versioning-blocks-of-content).
-- [ ] Add a checklist item for anything that needs to happen before this PR is merged, such as "needs technical review" or "change base branch."
-
-Adding or removing pages (delete if not applicable):
+<!-- 
+ADDING OR REMOVING PAGES (if so, uncomment):
 - [ ] Add/remove page in `website/sidebars.js`
 - [ ] Provide a unique filename for new pages
 - [ ] Add an entry for deleted pages in `website/vercel.json`
 - [ ] Run link testing locally with `npm run build` to update the links that point to deleted pages
+-->