Update issue templates (#1376)

* Update issue templates

* improve pull request template

* remove previous issue template

.github/ISSUE_TEMPLATE.md

-## 🎉 Description
-
-<!-- Briefly describe the issue you are experiencing (or the feature you want to see added to OpenZeppelin). Tell us what you were trying to do and what happened instead. **Remember, this is _not_ a place to ask for help debugging code; for that, we welcome you in the [OpenZeppelin Slack Channel](https://slack.openzeppelin.org/).** -->
-
-- [ ] 🐛 This is a bug report.
-- [ ] 📈 This is a feature request.
-
-<!-- Please check one of the above by placing an x in the box. -->
-
-## 💻 Environment
-
-Next, we need to know what your environment looks like.
-
-- Which version of OpenZeppelin are you using?
-- What network are you deploying to? Ganache? Ropsten?
-- How are you deploying your OpenZeppelin-backed contracts? truffle? Remix? Let us know!
-
-## 📝 Details
-
-Describe the problem you have been experiencing in more detail. Include as much information as you think is relevant. Keep in mind that transactions can fail for many reasons; context is key here.
-
-## 🔢 Code To Reproduce Issue [ Good To Have ]
-
-Please remember that with sample code it's easier to reproduce the bug and it's much faster to fix it.
-
-```
-insert short code snippets here
-```
-
-<!-- If your code is larger, consider linking us to a repo illustrating your issue. -->
-
-## 👍 Other Information
-
-<!-- List any other information that is relevant to your issue. Error logs, related issues, suggestions on how to fix, Stack Overflow links, forum links, etc. -->

.github/ISSUE_TEMPLATE/bug_report.md

+---
+name: Bug report
+about: Report a bug in OpenZeppelin
+
+---
+
+<!-- Briefly describe the issue you're experiencing. Tell us what you were trying to do and what happened instead. -->
+
+<!-- Remember, this is not a place to ask for help debugging code. For that, we welcome you in the OpenZeppelin Slack channel: https://slack.openzeppelin.org/. -->
+
+**💻 Environment**
+
+<!-- Tell us what version of OpenZeppelin you're using, and how you're using it: Truffle, Remix, etc. -->
+
+**📝 Details**
+
+<!-- Describe the problem you have been experiencing in more detail. Include as much information as you think is relevant. Keep in mind that transactions can fail for many reasons; context is key here. -->
+
+**🔢 Code to reproduce bug**
+
+<!-- We will be able to better help if you provide a minimal example that triggers the bug. -->

.github/ISSUE_TEMPLATE/feature_request.md

+---
+name: Feature request
+about: Suggest an idea for OpenZeppelin
+
+---
+
+**🧐 Motivation**
+<!-- Is your feature request related to a specific problem? Is it just a crazy idea? Tell us about it! -->
+
+**📝 Details**
+<!-- Please describe your feature request in detail. -->
+
+<!-- Make sure that you have reviewed the OpenZeppelin Contributor Guidelines. -->
+<!-- https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md -->

.github/PULL_REQUEST_TEMPLATE.md

 <!-- 0. 🎉 Thank you for submitting a PR! -->
 
-<!-- 1. **Does this close any open issues?** If so, list them here. If not, remove the `Fixes #` line. -->
+<!-- 1. Does this close any open issues? Please list them below. -->
 
-Fixes #
+<!-- Keep in mind that new features have a better chance of being merged fast if
+they were first discussed and designed with the maintainers. If there is no
+corresponding issue, please consider opening one for discussion first! -->
 
-# 🚀 Description
+Fixes #
 
-<!-- 2. Describe the changes introduced in this pull request -->
+<!-- 2. Describe the changes introduced in this pull request. -->
 <!--    Include any context necessary for understanding the PR's purpose. -->
 
-<!-- 3. Before submitting, please review the following checklist: -->
-
-- [ ] 📘 I've reviewed the [OpenZeppelin Contributor Guidelines](../blob/master/CONTRIBUTING.md)
-- [ ] ✅ I've added tests where applicable to test my new functionality.
-- [ ] 📖 I've made sure that my contracts are well-documented.
-- [ ] 🎨 I've run the JS/Solidity linters and fixed any issues (`npm run lint:fix`).
+<!-- 3. Before submitting, please make sure that you have:
+  - reviewed the OpenZeppelin Contributor Guidelines
+    (https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md),
+  - added tests where applicable to test new functionality,
+  - made sure that your contracts are well-documented, and
+  - run the JS/Solidity linters and fixed any issues (`npm run lint:fix`).
+-->