[Bug template] explain how to check versions, ask for config variables

Checking fish version is non-obvious as evidenced in #226.

Configuration variables often relevant, such as in #221.

Also stop asking for plugin manager as I've never seen that be relevant and it should only matter when uninstalling the plugin. Plus, only fisher is supported anyway. See #59.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -10,7 +10,7 @@ assignees: ""
 
 - [ ] My CLIs meet the [minimum version requirements](https://github.com/PatrickF1/fzf.fish#installation)
 - [ ] I have read through the [troubleshooting guide](https://github.com/PatrickF1/fzf.fish/wiki/Troubleshooting)
-- [ ] If I updated fzf.fish for the first time in over 6 months, I read the [migration guides](https://github.com/PatrickF1/fzf.fish/wiki/Migration-Guides) to make sure I'm caught up.
+- [ ] If I updated fzf.fish for the first time in over 6 months, I read the [migration guides](https://github.com/PatrickF1/fzf.fish/wiki/Migration-Guides) to make sure I'm caught up
 
 ## Describe the bug
 
@@ -22,12 +22,11 @@ If applicable, include screenshots here.
 
 Versions installed:
 
-- Fish: [e.g. 3.3.1]
-- fzf.fish: [e.g. 7.0]
-- plugin manager: [e.g. fisher 4.3.0]
+- Fish: [e.g. 3.3.1, check using `$version` instead of `fish --version`]
+- fzf.fish: [e.g. 7.0, [how to check this](https://github.com/PatrickF1/fzf.fish/wiki/Cookbook#how-can-i-check-which-version-of-fzffish-im-on)]
 - terminal: [e.g. iTerm]
 - OS: [e.g. macOS 11.4]
 
-## Additional context
+Which, if any, [configuration variables](https://github.com/PatrickF1/fzf.fish#configuration) such as `fzf_preview_file_cmd` are set?
 
-Anything else?
+## Additional context