Provide documentation for reporting issues with the Fleet UI (#613)

- Add 2 sections in `CONTRIBUTING.md` these 2 sections correspond to the "Bug report" and "Report a security vulnerability" issue templates
- Add "Is this an issue with the Fleet UI" to "Bug report" section in `CONTRIBUTING.md`. This includes a walkthrough for opening the browser's JS console and network requests
- Fix misspelled file name

.github/ISSUE_TEMPLATE/bug-report.md

@@ -7,7 +7,7 @@ assignees: ''
 
 ---
 
-**Fleet version** (`fleetctl version`): 
+**Fleet version** (Head to the "My account" page in the Fleet UI or run `fleetctl version`): 
 **Operating system** _(e.g. macOS 11.2.3)_: 
 **Web browser** _(e.g. Chrome 88.0.4324)_: 
 <hr/>
@@ -23,5 +23,6 @@ assignees: ''
 ### More info
 <!-- Any ideas?  -->
 
+<!-- If this is an issue with the Fleet UI: Please also [answer this question](https://github.com/fleetdm/fleet/blob/master/CONTRIBUTING.md#6-is-this-an-issue-with-the-fleet-ui). -->
 
 <!-- If this is a performance issue: Please [follow these steps](https://github.com/fleetdm/fleet/blob/master/docs/1-Using-Fleet/5-Monitoring-Fleet.md#debugging-performance-issues) to generate and attach a debug archive. -->