docker badge for readme

[metachris]

📝 Summary

To surface the docker images better

---

✅ I have run these commands

• make lint
• make test-race
• go mod tidy

[codecov-commenter]

Codecov Report

Merging #515 (f5f7dbd) into develop (54eeaa2) will decrease coverage by 1.43%.
The diff coverage is 64.43%.

❗ Your organization is not using the GitHub App Integration. As a result you may experience degraded service beginning May 15th. Please install the Github App Integration for your organization. Read more.

@@             Coverage Diff             @@
##           develop     #515      +/-   ##
===========================================
- Coverage    70.24%   68.81%   -1.43%     
===========================================
  Files            6        8       +2     
  Lines          541     1270     +729     
===========================================
+ Hits           380      874     +494     
- Misses         132      346     +214     
- Partials        29       50      +21     

Flag	Coverage Δ
unittests	68.81% <64.43%> (-1.43%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cli/types.go	0.00% <0.00%> (ø)
server/mock_types.go	100.00% <ø> (ø)
cli/main.go	12.98% <12.98%> (ø)
server/types.go	70.00% <70.00%> (ø)
server/service.go	75.74% <73.92%> (+3.73%)	⬆️
server/utils.go	82.23% <84.80%> (+14.66%)	⬆️
server/mock_relay.go	88.44% <90.81%> (+5.58%)	⬆️
server/relay_entry.go	90.00% <100.00%> (+8.75%)	⬆️

... and 1 file with indirect coverage changes