Update issue templates

.github/ISSUE_TEMPLATE/----.md

+---
+name: 特性申请
+about: 申请 mirai 添加新的特性
+title: ''
+labels: feature
+assignees: ''
+
+---
+
+以下相关功能将会被直接拒绝:
+- 资金相关: 红包, 转账
+- 主动加好友, 主动加群, 主动邀请加入群
+
+
+可以提交的内容:
+- 有较高使用频率的协议 (低频功能不接受提议)
+- 核心 API 的架构 / 功能上的建议 (欢迎)

.github/ISSUE_TEMPLATE/bug---.md

+---
+name: Bug 报告
+about: 提交一个 bug
+title: ''
+labels: "　bug　"
+assignees: ''
+
+---
+
+提交前请先确认:
+- [ ] 已经在现有 issue 列表中检查并未发现重复问题
+- [ ] 确认问题属于 `mirai-core`, 而不是 `mirai-console` 或其他
+
+若有报错, 请尽可能附加完整控制台日志或截图
+若无报错, 请尽可能描述如何复现这个问题

.github/ISSUE_TEMPLATE/feature_request.md

+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.