Update 1-building-a-basic-site.md

Added styling to specific useful text passages to make them more prominent to reader
Totally agree, and i'd have set it up if there was an in-built way to specify an info-box. The only other styling method I could have used was blockquote, but I didn't feel the blockquote style was appropriate for an info-box. 

Overall, I think these blocks are quite important for the reader to remember, so should be more prominent.