Recommend the use of https and mention git on building/checkout.html
https://bugs.webkit.org/show_bug.cgi?id=93657
Reviewed by Mark Rowe.
This page was quite out-dated. Stop mentioning about how to install subversion on OS X 10.4
because the paragraph right above it refers to buliding/tools.html for that.
Recommend the use of HTTPS connection for the Subversion checkout and also mention how to
checkout using a Git client.
* building/checkout.html:
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@125208
268f45cc-cd09-0410-ab3c-
d52691b4dbfc