chore: add ISSUE_TEMPLATE

Author: jinseopkim0

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,37 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: waiting-for-triage
+assignees: ''
+
+---
+**PLEASE READ**: If you have a support contract with Google, please create an issue in the
+[support console](https://cloud.google.com/support/) instead of filing on GitHub. This will ensure
+a timely response.
+
+We'd love to accept your patches and contributions to this project. There are just a few small
+guidelines you need to follow before opening an issue or a PR:
+
+1. Ensure the issue was not already reported.
+2. Open a new issue if you are unable to find an existing issue addressing your problem. Make sure
+   to include a title and clear description, as much relevant information as possible, and a code
+   sample or an executable test case demonstrating the expected behavior that is not occurring.
+3. Discuss the priority and potential solutions with the maintainers in the issue. The maintainers
+   would review the issue and add a label "Accepting Contributions" once the issue is ready for
+   accepting contributions.
+4. Open a PR only if the issue is labeled with "Accepting Contributions", ensure the PR description
+   clearly describes the problem and solution. Note that an open PR without an issue labeled with "
+   Accepting Contributions" will not be accepted.
+
+See
+also [CONTRIBUTING.adoc](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc/blob/main/CONTRIBUTING.adoc)
+.
+
+**Describe the bug**
+Please provide details of the problem, including the version that you are using.
+
+**Sample**
+If possible, please provide a test case or sample application that reproduces
+the problem. This makes it much easier for us to diagnose the problem and to verify that
+we have fixed it.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,4 @@
+contact_links:
+  - name: Google Cloud Support
+    url: https://cloud.google.com/support/
+    about: If you have a support contract with Google, please use the Google Cloud Support portal.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,37 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: waiting-for-triage
+assignees: ''
+
+---
+We'd love to accept your patches and contributions to this project. There are just a few small
+guidelines you need to follow before opening an issue or a PR:
+
+1. Ensure the issue was not already reported.
+2. Open a new issue if you are unable to find an existing issue addressing your problem. Make sure
+   to include a title and clear description, as much relevant information as possible, and a code
+   sample or an executable test case demonstrating the expected behavior that is not occurring.
+3. Discuss the priority and potential solutions with the maintainers in the issue. The maintainers
+   would review the issue and add a label "Accepting Contributions" once the issue is ready for
+   accepting contributions.
+4. Open a PR only if the issue is labeled with "Accepting Contributions", ensure the PR description
+   clearly describes the problem and solution. Note that an open PR without an issue labeled with "
+   Accepting Contributions" will not be accepted.
+
+See
+also [CONTRIBUTING.adoc](https://github.com/GoogleCloudPlatform/cloud-spanner-r2dbc/blob/main/CONTRIBUTING.adoc)
+.
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is and what version you are using. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.