docs: clean up PR checklist (#2721)

Author: hoffa

.github/PULL_REQUEST_TEMPLATE.md

@@ -7,20 +7,14 @@
 ### Checklist
 
 - [ ] Adheres to the [development guidelines](https://github.com/aws/serverless-application-model/blob/develop/DEVELOPMENT_GUIDE.md#development-guidelines)
-- [ ] Add/update [unit tests](https://github.com/aws/serverless-application-model/blob/develop/DEVELOPMENT_GUIDE.md#unit-testing-with-multiple-python-versions) using:
-    - [ ] Correct values
-    - [ ] Bad/wrong values (None, empty, wrong type, length, etc.)
-    - [ ] [Intrinsic Functions](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference.html)
+- [ ] Add/update [transform tests](https://github.com/aws/serverless-application-model/blob/develop/DEVELOPMENT_GUIDE.md#unit-testing-with-multiple-python-versions)
+    - [ ] Using correct values
+    - [ ] Using wrong values
 - [ ] Add/update [integration tests](https://github.com/aws/serverless-application-model/blob/develop/INTEGRATION_TESTS.md)
-- [ ] Update documentation
-- [ ] Verify transformed template deploys and application functions as expected
-- [ ] Do these changes include any template validations?
-    - [ ] Did the newly validated properties support intrinsics prior to adding the validations? (If unsure, please review [Intrinsic Functions](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference.html) before proceeding).
-        - [ ] Does the pull request ensure that intrinsics remain functional with the new validations?
 
 ### Examples?
 
-Please reach out in the comments, if you want to add an example. Examples will be 
-added to `sam init` through https://github.com/awslabs/aws-sam-cli-app-templates/
+Please reach out in the comments if you want to add an example. Examples will be 
+added to `sam init` through [aws/aws-sam-cli-app-templates](https://github.com/aws/aws-sam-cli-app-templates).
 
 By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

DEVELOPMENT_GUIDE.md

@@ -157,7 +157,7 @@ Integration tests are covered in detail in the [INTEGRATION_TESTS.md file](INTEG
 
 ## Development guidelines
 
-1. **Do not resolve [intrinsic functions](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference.html).** Adding [`AWS::LanguageExtensions`](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-languageextension-transform.html) before the `AWS::Serverless-2016-10-31` transform resolves most of them (see https://github.com/aws/serverless-application-model/issues/2533). Use [`Property`](https://github.com/aws/serverless-application-model/blob/c5830b63857f52e540fec13b29f029458edc539a/samtranslator/model/__init__.py#L36-L45) or [`PassThroughProperty`](https://github.com/aws/serverless-application-model/blob/dd79f535500158baa8e367f081d6a12113497e45/samtranslator/model/__init__.py#L48-L56) instead of [`PropertyType`](https://github.com/aws/serverless-application-model/blob/develop/samtranslator/model/__init__.py#L13-L33).
+1. **Do not resolve [intrinsic functions](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference.html).** Adding [`AWS::LanguageExtensions`](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-languageextension-transform.html) before the `AWS::Serverless-2016-10-31` transform resolves most of them (see https://github.com/aws/serverless-application-model/issues/2533). For new properties, use [`Property`](https://github.com/aws/serverless-application-model/blob/c5830b63857f52e540fec13b29f029458edc539a/samtranslator/model/__init__.py#L36-L45) or [`PassThroughProperty`](https://github.com/aws/serverless-application-model/blob/dd79f535500158baa8e367f081d6a12113497e45/samtranslator/model/__init__.py#L48-L56) instead of [`PropertyType`](https://github.com/aws/serverless-application-model/blob/c39c2807bbf327255de8abed8b8150b18c60f053/samtranslator/model/__init__.py#L13-L33).
 2. **Do not break backward compatibility.** As rule of thumb, a specific SAM template should always transform into the same CloudFormation template. Do not change logical IDs. Add opt-in properties for breaking changes. There are some exceptions, such as changes that do not impact resources (e.g. [`Metadata`](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/metadata-section-structure.html)) or abstractions that can by design change over time.
 3. **Stick as close as possible to the underlying CloudFormation properties.** This includes both property names and values. This ensures we can pass values to CloudFormation and let it handle any intrinsic functions. In some cases, it also allows us to pass all properties as-is to a resource, which means customers can always use the newest properties, and we don’t spend effort maintaining a duplicate set of properties.
 4. **Only validate what’s necessary.** Do not validate properties if they’re passed directly to the underlying CloudFormation resource.