corrected README.md Events example code
corrected README.md Events example code

jantimon/html-webpack-plugin,SimenB/html-webpack-plugin,SimenB/html-webpack-plugin,SpaceK33z/html-webpack-plugin,SpaceK33z/html-webpack-plugin,jantimon/html-webpack-plugin,ampedandwired/html-webpack-plugin,ampedandwired/html-webpack-plugin