Add flags to readme

[challapradyumna]

Updated documentation with available flags.

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #67 (b835f96) into master (71fbbbf) will decrease coverage by 2.26%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #67      +/-   ##
==========================================
- Coverage   72.08%   69.82%   -2.27%     
==========================================
  Files          12       12              
  Lines         996      898      -98     
==========================================
- Hits          718      627      -91     
+ Misses        216      211       -5     
+ Partials       62       60       -2     

Impacted Files	Coverage Δ
pkg/service/deregistrator.go	43.93% <0.00%> (-3.95%)	⬇️
pkg/service/metrics.go	80.95% <0.00%> (-3.67%)	⬇️
pkg/service/sqs.go	69.23% <0.00%> (-3.50%)	⬇️
pkg/service/nodes.go	82.71% <0.00%> (-2.40%)	⬇️
pkg/service/autoscaling.go	76.47% <0.00%> (-2.11%)	⬇️
pkg/service/target.go	76.47% <0.00%> (-1.80%)	⬇️
pkg/service/events.go	82.85% <0.00%> (-1.76%)	⬇️
pkg/service/server.go	59.20% <0.00%> (-1.49%)	⬇️
pkg/service/manager.go	70.58% <0.00%> (-0.59%)	⬇️
pkg/service/elb.go	100.00% <0.00%> (ø)
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 71fbbbf...b835f96. Read the comment docs.

[eytan-avisror]

Thanks for adding this @challapradyumna
Can you center the columns? I think you can do that by adding :--:, e.g.

| Name | Default | Type | Description |
|:------:|:---------:|:------:|:-------------:|