ICSHWI-10603: Update help and about pages

From https://jira.esss.lu.se/browse/ICSHWI-10603

About

• doesn't mention IOC-host warnings
• "users without access" paragraph could be removed
• "swagger UI" means nothing to our users
• we don't provide data about the actual path to the rest API

Help

• refers to our beta slack channel instead of SD
• third bullet requires update (iocs/), also down in FAQ