Add holiday and weekend disclaimers to compensation timeline.md

[astrogeco]

One more place to add the weekend text: https://github.com/GSA-TTS/identity-idva-docs/blob/af3895e180ce3c562b62743786681ef254b44916/index.html#L120-L126

Might also want to add the "team will inspect images, etc" text somewhere

[astrogeco]

@ptolleyedc still missing one more section in index page. Source content is in gsa-faqs.html