Clean up --help for deprecated flags

[mkungla]

It is confusing at the moment is some flag deprecated or not, remove duplicated entries

e.g.

coverage-reporter/src/coverage_reporter/cli/cmd.cr

Lines 147 to 149 in 63c6233

	parser.on("-p", "--parallel", "Set the parallel flag. Requires webhook for completion (coveralls done)") do
	opts.parallel = true
	end

coverage-reporter/src/coverage_reporter/cli/cmd.cr

Lines 295 to 297 in 63c6233

	parser.on("-p", "--parallel", "DEPRECATED: Set the parallel flag. Requires webhook for completion (coveralls done)") do
	opts.parallel = true
	end

[afinetooth]

@mkungla Thanks for reporting this. I agree.

I have asked for a review and bump in priority. I'll update you here with any changes.