Merge pull request #377 from mbj/fix/improve-cli-help-wording

Fix wording in --ignore-subject help description

lib/mutant/cli.rb

@@ -152,7 +152,7 @@ module Mutant
     #
     # @api private
     def add_filter_options(opts)
-      opts.on('--ignore-subject PATTERN', 'Ignore subjects that match PATTERN') do |pattern|
+      opts.on('--ignore-subject EXPRESSION', 'Ignore subjects that match EXPRESSION as prefix') do |pattern|
         add_matcher(:ignore_expressions, config.expression_parser.(pattern))
       end
     end

spec/unit/mutant/cli_spec.rb

@@ -127,7 +127,7 @@ Environment:
 Options:
         --expected-coverage COVERAGE Fail unless COVERAGE is not reached exactly, parsed via Rational()
         --use INTEGRATION            Use INTEGRATION to kill mutations
-        --ignore-subject PATTERN     Ignore subjects that match PATTERN
+        --ignore-subject EXPRESSION  Ignore subjects that match EXPRESSION as prefix
         --fail-fast                  Fail fast
         --version                    Print mutants version
     -d, --debug                      Enable debugging output