Update docs to reflect the changes for the -http flag

[rakyll]

Docs are stale, -http flag now supports host:port.

[codecov-io]

Codecov Report

Merging #180 into master will decrease coverage by 0.19%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master     #180     +/-   ##
=========================================
- Coverage   54.42%   54.23%   -0.2%     
=========================================
  Files          32       32             
  Lines        6355     6186    -169     
=========================================
- Hits         3459     3355    -104     
+ Misses       2535     2470     -65     
  Partials      361      361

Impacted Files	Coverage Δ
internal/driver/cli.go	77.2% <ø> (ø)	⬆️
profile/prune.go	72% <0%> (-0.35%)	⬇️
profile/merge.go	85.77% <0%> (+0.89%)	⬆️
profile/profile.go	61.88% <0%> (+2.91%)	⬆️
profile/proto.go	83.25% <0%> (+3.73%)	⬆️

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[aalexand]

Maybe it would be a bit more convenient if we treated -http as "localhost:" when just "" is specified.

[rakyll]

Sounds good to support "" as -http. I will send a PR for that.

[rakyll]

@aalexand, can you merge this change? I don't have the privileges to do it myself.