minor fixes for web-api

[cneud]

• typo corrected ("iff" -> "if")
• use https for OCR-D website and Apache license

[mweidling]

I think the iff was intended by @kba because it's a logical term meaning "if and only if". But it confused others as well, so we might write it more explicitly (@kba)?

[cneud]

Yeah I was unsure about that too, but since this is in documentation and not actual code...let's see what @kba thinks.

[kba]

Yeah, it was meant as "if and only if" - I like precise language :) But since it confuses you, let's drop it.