Update issue templates

.github/ISSUE_TEMPLATE/-bounty-title-.md

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+---
+name: "<Bounty title>"
+about: Start here to publish a new GitCoin Bounty
+title: A General-purpose NFT Marketplace
+labels: ''
+assignees: ''
+
+---
+
+## General
+#### Discuss
+Please join our [Discord Dev Chat](https://iotex.io/devdiscord) and reach out to `Simone_IoTeX` to discuss the project 
+
+#### Follow Us
+[iotex.io](https://iotex.io) | [Telegram](https://t.me/IoTeXGroup) | [Twitter](https://twitter.com/iotex_io) | [Medium](https://medium.com/@iotex) | [Reddit](https://www.reddit.com/r/IoTeX)
+
+## Bounty Description
+What the applicants are supposed to build?
+
+## Context
+If it's useful, explain the context in which this project is inserted such taht the applicatns can better understand the intent
+
+## Acceptance criteria
+Set clear and verifiable acceptance criteria for the project. If required, split into milestones and split the following Reward section accordingly:
+
+**Milestone 1**
+* [ ] Acceptance criteria 1
+* [ ] Acceptance criteria 2
+
+**Milestone M**
+* [ ] Acceptance criteria N
+
+## Time estimation
+If there is a deadline, or a specific requirement for the time required to develop this project, please set it here
+
+## Reward
+Set the reward for this bounty (in USD). Depending on the Acceptance criteria section, this could be split into milestones.
+
+* [ ] Milestone I: X USD
+* [ ] Milestone II: Y USD
+...