chore(github): add some tips to improve pull requests (spinnaker#6825)

* chore(github): add tips to improve pull requests

* english is hard

.github/PULL_REQUEST_TEMPLATE.md

@@ -12,3 +12,39 @@ When filling out a pull request, please consider the following:
 * Add a comment to @spinnaker/reviewers for review if your issue has been outstanding for more than 3 days.
 
 Note that we are unlikely to accept pull requests that add features without prior discussion. The best way to propose a feature is to open an issue first and discuss your ideas there before implementing them.
+
+
+----------
+# Helpful Tips
+
+## Add screenshots and annotations
+<kbd>![](https://cl.ly/744faf8f96d7/download/Image%202019-04-08%20at%2012.35.32.png)</kbd>
+- In OSX Mojave, you can capture screenshots and add annotations. https://support.apple.com/en-us/HT201361
+- Another app you can use is https://www.getcloudapp.com/.
+
+## Add a gif to show an action
+GIFs are great to show an action, however they sometimes move too fast. 
+One way to improve them is to capture 3 pieces of content:
+- screenshot before an action
+- screenshot after the action
+- gif of the action
+- You can edit a gif using https://ezgif.com/
+
+## Put a border around a screenshot/gif
+Add a border to help improve the readability.
+```html
+<kbd>![](https://www.spinnaker.io/assets/images/spinnaker-logo-inline.svg)</kbd>
+```
+
+## Add expandable sections
+<details>
+<summary>Add expandable sections to hide away large code blocks/images or reduce the motion of a gifs</summary>
+
+```js
+const example = 'spinnaker spinnaker SPINNAKER';
+```
+
+<kbd>![](https://www.spinnaker.io/assets/images/spinnaker-logo-inline.svg)</kbd>
+
+<kbd>![](https://cl.ly/90d191c48dab/download/spinnaker-loader.gif)</kbd>
+</details>