docs: update pull request template (#2329)

* docs: update pull request template

Signed-off-by: Morre <[email protected]>

* fix some markdown lint errors

Signed-off-by: André Bauer <[email protected]>

* fixup! fix some markdown lint errors

Signed-off-by: Morre <[email protected]>

Co-authored-by: André Bauer <[email protected]>

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,6 +1,6 @@
 <!--
 Thank you for contributing to prometheus-community/helm-charts.
-Before you submit this PR we'd like to make sure you are aware of our technical requirements and best practices:
+Before you submit this pull request we'd like to make sure you are aware of our technical requirements and best practices:
 
 * https://github.com/prometheus-community/helm-charts/blob/main/CONTRIBUTING.md#technical-requirements
 * https://helm.sh/docs/chart_best_practices/
@@ -10,30 +10,38 @@ For a quick overview across what we will look at reviewing your PR, please read
 // TODO: add a REVIEW_GUIDELINES.md in prometheus-community/helm-charts
 * https://github.com/helm/charts/blob/master/REVIEW_GUIDELINES.md
 
-Following our best practices right from the start will accelerate the review process and help get your PR merged quicker.
+Following our best practices right from the start will accelerate the review process and help get your pull request merged quicker.
 
-When updates to your PR are requested, please add new commits and do not squash the history.
+When updates to your pull request are requested, please add new commits and do not squash the history.
 This will make it easier to identify new changes.
-The PR will be squashed anyways when it is merged.
+The pull request will be squashed anyways when it is merged.
 Thanks.
 
 For fast feedback, please @-mention maintainers that are listed in the Chart.yaml file.
 
 Please make sure you test your changes before you push them.
-Once pushed, GitHub Actions will run across your changes and do some initial checks and linting.
+Once the pull request is opened, GitHub Actions will run across your changes and do some initial checks and linting.
 These checks run very quickly.
 Please check the results.
+If you are contributing to this repository for the first time, a maintainer will need to approve those checks to run.
+They are automatically requested as reviewers and will approve the workflows or ask you for changes once they get to it.
+
 We would like these checks to pass before we even continue reviewing your changes.
 -->
-#### What this PR does / why we need it:
+
+<!-- markdownlint-disable-next-line first-line-heading -->
+#### What this PR does / why we need it
 
 #### Which issue this PR fixes
+
 *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*
-  - fixes #
 
-#### Special notes for your reviewer:
+- fixes #
+
+#### Special notes for your reviewer
 
 #### Checklist
+
 <!-- [Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.] -->
 - [ ] [DCO](https://github.com/prometheus-community/helm-charts/blob/main/CONTRIBUTING.md#sign-off-your-work) signed
 - [ ] Chart Version bumped