validation.md: fix _validation.scss file reference (#31795)
validation.md: fix _validation.scss file reference (#31795)


GerHobbelt/bootstrap,tjkohli/bootstrap,coliff/bootstrap,GerHobbelt/bootstrap,inway/bootstrap,twbs/bootstrap,twbs/bootstrap,inway/bootstrap,inway/bootstrap,m5o/bootstrap,GerHobbelt/bootstrap,m5o/bootstrap,tjkohli/bootstrap,coliff/bootstrap