Update "README.md" file
Update "README.md" file

- Fix wrong titles
- Remove deprecated validators
- Sort validators appendix alphabetically
- Update Markdown syntax for titles
- Update number of existing validators

rozehnal/Validation,Respect/Validation,rogeriopradoj/Validation,hudolfhess/Validation,riyan8250/Validation,Respect/Validation,regdos/Validation,jpjoao/Validation,osiux/Validation,Whyounes/Validation,Ye-Yong-Chi/Validation,ahmetgunes/Validation,maliayas/Validation,mrsoto/Validation,guilhermesiani/Validation,solvire/Validation,mubassirhayat/Validation,zinovyev/Validation,lalocespedes/Validation,thedavidmeister/Validation