[repo] Add minimal reproducible example link to the issue template

[reyang]

Per suggestion from @Kielek open-telemetry/opentelemetry-dotnet-contrib#1716 (comment).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.67%. Comparing base (6250307) to head (d2aad98).
Report is 221 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5610      +/-   ##
==========================================
+ Coverage   83.38%   85.67%   +2.29%     
==========================================
  Files         297      254      -43     
  Lines       12531    10982    -1549     
==========================================
- Hits        10449     9409    -1040     
+ Misses       2082     1573     -509     

Flag	Coverage Δ
unittests	?
unittests-Solution-Experimental	85.62% <ø> (?)
unittests-Solution-Stable	85.67% <ø> (?)
unittests-Unstable-Core	19.90% <ø> (?)

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see 115 files with indirect coverage changes

[CodeBlanch]

LGTM