update issue template structure

.github/ISSUE_TEMPLATE/default.md

@@ -0,0 +1,54 @@
+---
+name: Bug Report
+about: Use this template for all issues
+---
+<!--
+Before filing an issue, please check if vim-go's help addresses your problem (see `:help go-troubleshooting`).
+
+Consider executing `:GoReportGitHubIssue` to populate much of this information automatically.
+-->
+### What did you do? (required: The issue will be **closed** when not provided)
+
+<!--
+If possible, please provide clear steps for reproducing the problem.
+-->
+
+### What did you expect to happen?
+
+### What happened instead?
+
+### Configuration (**MUST** fill this out):
+
+#### vim-go version:
+
+####  `vimrc` you used to reproduce:
+<!--
+Use a *minimal* vimrc with other plugins disabled; do not link to a 2,000 line vimrc.
+
+If this is not provided or is obviously incomplete, the issue may be unceremoniously closed.
+-->
+<!-- vimrc -->
+<details><summary>vimrc</summary>
+
+```vim
+
+```
+</details>
+
+#### Vim version (first three lines from `:version`):
+<!-- :version -->
+
+#### Go version (`go version`):
+<!-- go version -->
+
+#### Go environment
+<details><summary><code>go env</code> Output:</summary><br><pre>
+<!-- go env -->
+
+</pre></details>
+
+#### gopls version
+<details><summary><code>gopls version</code> Output:</summary><br><pre>
+<!-- gopls version -->
+
+</pre></details>