docs: add docs on how to get the configuration values
docs: add docs on how to get the configuration values

mzgol/karma-browserstack-launcher,jackspirou/karma-browserstack-launcher,luhmann/karma-browserstack-launcher,Dignifiedquire/karma-browserstack-launcher,szarouski/karma-browserstack-launcher,shirish87/karma-browserstack-launcher,karma-runner/karma-browserstack-launcher