chore(github): add github templates (#50)

Author: glebec

.github/CONTRIBUTING.md

@@ -0,0 +1,19 @@
+# Contributing to this Project
+
+Thank you for your interest. `eslint-config-fullstack` generally conforms to the following principles:
+
+* Configuring rules
+  * Maintain a list of every base ESLint rule & every `eslint-plugin-react` rule. This means tracking changes to those packages, which [Greenkeeper](https://greenkeeper.io/) helps with.
+    * When a new version of those deps is published, read the changelog and add / modify the relevant rules in the corresponding Greenkeeper branch. **Do not** simply merge the GK branch as-is.
+	* When simply turning rules off, set them to `0`, do not delete them
+	* Delete deprecated rules only
+    * Keep the rule summary, verbatim from the corresponding API reference, as a comment following the rule
+  * Activate rules whose pedagogical and/or stylistic value outweighs their annoyance
+    * If a rule *almost definitely* indicates broken code, set it to `2` (error)
+    * If a rule *quite possibly* flags code that could still work, set it to `1` (warning)
+* Code style
+  * This repo uses [Prettier](https://prettier.io/) and [lint-staged](https://github.com/okonet/lint-staged) to automatically maintain formatting.
+  * If you prefer, you can run Prettier yourself on the code to preview how it will be auto-formatted, using `npm run prettify` or activating an [editor plugin](https://prettier.io/docs/en/editors.html)
+* Respect [SEMVER](https://semver.org/) when publishing to npm
+  * Turning rules off will count as a minor change as nobody's code should break (in theory)
+  * Turning rules on or changing their options should count as a major change as linting may now result in nonzero exit codes where none existed before

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,9 @@
+For bugs, please include the following:
+
+* What is the expected behavior?
+* What is the actual behavior?
+* What steps reproduce the behavior?
+
+---
+
+*Issue description here…*

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,17 @@
+### Assignee Tasks
+
+Please check all that apply.
+
+- [ ] referenced any relevant issue(s)
+- [ ] Adding new rule(s)?
+  - [ ] Included rule summary verbatim from docs as a comment
+  - [ ] Placed in the right section (stylistic / node / etc.), in alphabetical order
+  - [ ] Set to `0` (off), `1` (warn), or `2` (error) as spec'd in contributing guidelines
+- [ ] Changing active rule(s) severity?
+  - [ ] Set to `1` (warn), or `2` (error) as spec'd in contributing guidelines
+- [ ] Removing rule(s)?
+  - [ ] Set to `0` if disabling, or delete _only if deprecated_
+
+---
+
+*Your PR Notes Here*