[guide] fix broken deep link to 'testing--yup'
[guide] fix broken deep link to 'testing--yup'

codelegant/JavaScript,pokelondon/javascript,addshoppers/javascript,getjll/JavaScript-Style-Guide,allanfish/javascript,LodoSoftware/javascript-style-guide,practicefusion/javascript,webcoding/javascript-style-guide,airbnb/javascript,whichdigital/javascript-coding-standards,LodoSoftware/javascript-style-guide,appcom-interactive/javascript,codelegant/JavaScript,ljharb/javascript,naustudio/javascript,nulogy/javascript,bl00mber/javascript,cloudability/javascript-style-guide,xalexec/javascript,naustudio/javascript