Adding contributing guide

.github/CONTRIBUTING.md

@@ -0,0 +1,32 @@
+# Contributing
+
+Hi! Thank you for considering contributing to GraphQLite. You'll
+find below useful information about how to contribute to the GraphQLite project.
+
+## Contributing code
+
+### Install from sources
+
+1. Verify your PHP version (>= 7.1)
+2. Fork this repository
+3. Run `composer install`
+
+### Working with git
+
+1. Create your feature branch (`git checkout -b my-new-feature`)
+2. Commit your changes (`git commit -am 'Add some feature'`)
+3. Push to the branch (`git push origin my-new-feature`)
+4. Create a new pull request
+
+### Testing
+
+1. Run static analyzer (`composer phpstan`)
+2. Run tests (`./vendor/bin/phpunit`)
+
+## Reporting bugs and feature request
+
+Your issue or feature request may already be reported!
+Please search on the [issue tracker](../../../issues) before creating one.
+
+If you do not find any relevant issue or feature request, feel free to
+add a new one!

.travis.yml

@@ -2,9 +2,10 @@ language: php
 cache:
   directories:
     - $HOME/.composer/cache
-matrix:
+jobs:
   include:
-    - php: 7.3
+    - stage: test
+      php: 7.3
       env: PREFER_LOWEST=""
       before_script:
         - &composerupdate
@@ -15,30 +16,32 @@ matrix:
         - composer phpstan
       after_script:
         - ./vendor/bin/coveralls -v
-    - php: 7.2
+    - stage: test
+      php: 7.2
       env: PREFER_LOWEST=""
       before_script:
         - *composerupdate
       script:
         - *phpunit
-    - php: 7.1
+    - stage: test
+      php: 7.1
       env: PREFER_LOWEST=""
       before_script:
         - *composerupdate
       script:
         - *phpunit
-    - php: 7.1
+    - stage: test
+      php: 7.1
       env: PREFER_LOWEST="--prefer-lowest"
       before_script:
         - *composerupdate
       script:
         - *phpunit
-    - name: "Doc generation"
+    - stage: doc
+      if: branch = master
+      name: "Doc generation"
       language: node_js
       node_js: 8
-      branches:
-        only:
-          - master
       cache:
         yarn: true
       script: