Add GitHub issue template

Author: dmitry-ivanov

.github/ISSUE_TEMPLATE/3_Support_Laravel_version.md

@@ -0,0 +1,24 @@
+---
+name: "⚒️ Support Laravel Version"
+about: 'If you want to support a new Laravel version.'
+---
+
+### Follow these steps:
+
+  1. In the package's `composer.json` file:
+    - Set all of the `illuminate/%` packages to the new version, i.e. `^6.0`;
+    - Set the `php` version according to the Laravel's `composer.json`;
+      - Make proper fixes in the `php` list within the `.travis.yml` file;
+    - Set versions for all of the packages according to the Laravel's `composer.json`;
+  2. Add a new row in the `README.md` file for the new version.
+  3. Open the PR:
+    - Make sure that all of the CI checks are passing;
+
+### Next steps from my side:
+
+  1. Merge the PR.
+  2. Create the new branch, i.e. `6.x`.
+  3. For the new branch, within the `README.md` file:
+    - Fix the branch for badges, i.e., from `master` to `6.x`;
+    - Set the branch for the installation command, i.e., `illuminated/package:^6.0`;
+  4. Create a new release.