change the github issue template

I have noticed that too many new issues have not used the issue template
in the expected manner. Primarily because most people opening issues are
not accustomed to Github Markdown syntax. So change the template to be
exclusively a comment that provides advice regarding what information
will help the fish community resolve a issue.

.github/ISSUE_TEMPLATE.md

@@ -1,21 +1,14 @@
-<!-- check if this problem is already solved! github.com/issues?q=is:issue+user:fish-shell -->
-- [ ] Have you checked if problem occurs with [fish 2.5.0](/fish-shell/fish-shell/releases/tag/2.5.0)?
-- [ ] Tried fish without third-party customizations *(check `sh -c 'env HOME=$(mktemp -d) fish'`)*?
+<!--
+Please tell us which fish version you are using by executing the following:
 
-**fish version installed** *(`fish --version`)*:
+  fish --version
+  echo $version
 
-**OS/terminal used**:
+Please tell us which operating system and terminal you are using. The output of `uname -a` and `echo $TERM` may be helpful in this regard although other commands might be relevant in your specific situation.
 
-Talk about the the issue here.
+Please tell us if you tried fish without third-party customizations by executing this command and whether it affected the behavior you are reporting:
 
-## Reproduction steps
-1. step one
-2. …
+  sh -c 'env HOME=$(mktemp -d) fish'
 
-<!-- Hard to explain? Post a screen recording on asciinema.org then link it here -->
-
-## Results
-```console
-~ $ math 2 + 2
-5
-```
+Tell us how to reproduce the problem. Including an asciinema.org recording is useful for problems that involve the visual display of fish output such as its prompt.
+-->