Add v5.1.0 to migration guide, update v5.2.0 additions
Add v5.1.0 to migration guide, update v5.2.0 additions

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