Adding extra information about me on README file

[alexanmtz]

Change the text of the './README.md' file, keeping the current content, and extend it by listing my a resume of my experience speaking in conferences using the following conferences I've spoken:

• React Advanced London – London – 01/06/2019 – A presentation on React Native stage about Accessibility for React Native Apps
• Sencha Community Days 05/2019 – a presentation about how we scale and manage the UI in your React apps to keep it simple and consistent
• Qcon 2015, 03/2015, – Speaks about Multiplatform application development
• The developer’s conference 2014 – 07/2014 and Front in Fortaleza 2014 – Speaks about the perception of performance
• FISL 13, 14– Fórum Internacional de Software Livre, 2013 and 2014 – Speaks about Bootstrap and Developing jQuery UI plugins and testing with Jasmine

Add this content before the section, "And That's my activity" with a title like "Some conferences I've been speaking". Fix any grammar or language mistakes in the existing content as well.