doc: improve github templates by using comments

Use HTML comments to reduce potential noise in github templates.
Also, improve flow of the pull request, making it easier to read.

PR-URL: #5710
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

.github/ISSUE_TEMPLATE.md

@@ -1,14 +1,23 @@
-_Thanks for wanting to report an issue you've found in Node.js. Please delete
-this text and fill in the template below. If unsure about something, just do as
-best as you're able._
-
-_Note that it will be much easier for us to fix the issue if a test case that
-reproduces the problem is provided. Ideally this test case should not have any
-external dependencies. We understand that it is not always possible to reduce
-your code to a small test case, but we would appreciate to have as much data as
-possible. Thank you!_
-
-* **Version**: _output of `node -v`_
-* **Platform**: _either `uname -a` output, or if Windows, version and 32-bit or
-  64-bit_
-* **Subsystem**: _optional. if known - please specify affected core module name_
+<!--
+Thanks for wanting to report an issue you've found in Node.js. Please fill in
+the template below by replacing the html comments with an appropriate answer.
+If unsure about something, just do as best as you're able.
+
+version: usually output of `node -v`
+platform:  either `uname -a` output, or if Windows, version and 32 or 64-bit.
+subsystem:  optional -- if known please specify affected core module name.
+
+It will be much easier for us to fix the issue if a test case that reproduces
+the problem is provided. Ideally this test case should not have any external
+dependencies. We understand that it is not always possible to reduce your code
+to a small test case, but we would appreciate to have as
+much data as possible.
+
+Thank you!
+-->
+
+* **Version**:
+* **Platform**:
+* **Subsystem**:
+
+<!-- Enter your issue details below this comment. -->

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,24 +1,33 @@
-### Pull Request check-list
+<!--
+Thank you for submitting a pull request to Node.js. Before you submit, please
+review below requirements and walk through the checklist. You can 'tick'
+a box by using the letter "x": [x].
 
-_Please make sure to review and check all of these items:_
+Run the test suite by invoking: `make -j4 lint test` on linux or
+`vcbuild test nosign` on Windows.
 
-- [ ] Does `make -j8 test` (UNIX) or `vcbuild test nosign` (Windows) pass with
-  this change (including linting)?
-- [ ] Is the commit message formatted according to [CONTRIBUTING.md][0]?
-- [ ] If this change fixes a bug (or a performance problem), is a regression
-  test (or a benchmark) included?
-- [ ] Is a documentation update included (if this change modifies
-  existing APIs, or introduces new ones)?
+If this aims to fix a regression or you’re adding a feature, make sure you also
+write a test. Finally – if possible – a benchmark that quantifies your changes.
 
-_NOTE: these things are not required to open a PR and can be done
-afterwards / while the PR is open._
+Finally, read through our contributors guide and make adjustments as necessary:
+https://github.com/nodejs/node/blob/master/CONTRIBUTING.md
+-->
 
-### Affected core subsystem(s)
+##### Checklist
 
-_Please provide affected core subsystem(s) (like buffer, cluster, crypto, etc)_
+<!-- remove lines that do not apply to you -->
 
-[0]: https://github.com/nodejs/node/blob/master/CONTRIBUTING.md#step-3-commit
+- [ ] tests and code linting passes
+- [ ] a test and/or benchmark is included
+- [ ] documentation is changed or added
+- [ ] the commit message follows commit guidelines
 
-### Description of change
 
-_Please provide a description of the change here._
+##### Affected core subsystem(s)
+
+<!-- provide affected core subsystem(s) (like doc, cluster, crypto, etc) -->
+
+
+##### Description of change
+
+<!-- provide a description of the change below this comment -->