Updated contributing docs (#5028)

* Updated contributing docs

* Combined docs bullet points

* Removed screenshots

* Added validation wording

.github/pull_request_template.md

 <!--- Provide a general summary of your changes in the Title above -->
 
 ## Description
-<!--- Describe your changes in detail -->
+<!--- Describe your changes in detail including motivation and any context -->
 
 ## Related Issue
-<!--- This project only accepts pull requests related to open issues (GitIssues) -->
 <!--- If suggesting a new feature or change, please discuss it in an issue first -->
 <!--- If fixing a bug, there should be an issue describing it with steps to reproduce -->
 <!--- Please link to the issue here: -->
 
-## Motivation and Context
-<!--- Why is this change required? What problem does it solve? -->
-
-## How Has This Been Tested?
-<!--- Please describe in detail how you tested your changes. -->
-<!--- Include details of your testing environment, and the tests you ran to -->
-<!--- see how your change affects other areas of the code, etc. -->
-
-## Screenshots (if appropriate):
+## How Has This Been Validated?
+<!--- All changes need to be validated to confirm that they produce -->
+<!--- scientifically accurate results. -->
+<!--- If your changes include any new algorithms or changes to existing algorithms, -->
+<!--- please indicate any publications or references for them. -->
+<!--- If you manually validated the changes please indicate -->
+<!--- what data you used and how you checked the results. -->
 
 ## Types of changes
 <!--- What types of changes does your code introduce? Put an `x` in all the boxes that apply: -->
@@ -25,6 +22,7 @@
 - [ ] New feature (non-breaking change which adds functionality)
 - [ ] Documentation change (update to the documentation; no code change)
 - [ ] Breaking change (fix or feature that would cause existing functionality to change)
+- [ ] Infrastructure change (changes to things like CI or the build system that do not impact users)
 
 ## Checklist:
 <!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
@@ -32,10 +30,8 @@
 <!--- - [ ] My code follows the code style of this project. -->
 - [ ] I have read and agree to abide by the [Code of Conduct](https://github.com/USGS-Astrogeology/ISIS3/blob/dev/Code-Of-Conduct.md)
 - [ ] I have read the [**CONTRIBUTING**](https://github.com/USGS-Astrogeology/ISIS3/blob/dev/CONTRIBUTING.md) document.
-- [ ] My change requires a change to the documentation.
-- [ ] I have updated the documentation accordingly.
+- [ ] My change requires a change to the documentation and I have updated the documentation accordingly.
 - [ ] I have added tests to cover my changes.
-- [ ] All new and existing tests passed.
 - [ ] I have added myself to the [.zenodo.json](https://github.com/USGS-Astrogeology/ISIS3/blob/dev/.zenodo.json) document.
 - [ ] I have added any user impacting changes to the [CHANGELOG.md](https://github.com/USGS-Astrogeology/ISIS3/blob/dev/CHANGELOG.md) document.
 

CONTRIBUTING.md

@@ -46,11 +46,3 @@ by discussion, compromise on the proposed change, or withdrawal of the proposed
 When making a bug fix contribution, please add the [bug](https://github.com/USGS-Astrogeology/ISIS3/pulls?q=is%3Apr+label%3Abug+) label to your pull request. This will automatically cherry-pick your PR into the latest release branch so that it can be distributed in the next bug fix release.
 
 When making a contribution for the first time, please add your name to the `.zenodo.json file.` We strongly recommend adding your affiliation and ORCiD to the `zenodo.json` file. These additions only have to happen once.
-
-# Becoming a Committer
-
-All contributors who land a non-trivial contribution should be on-boarded in a timely manner,
-and added as a committer, and be given write access to the repository.
-
-Committers are expected to follow this policy and continue to send pull requests, go through
-proper review, and have other committers merge their pull requests.