docs(security): 2.4.0 at-rest encryption key advisory + --encryption-key - #79

Changed pages include:

• index.html - view
• 1.x/index.html - view
• 404.html - view
• contributing/index.html - view
• core/index.html - view
• deployment/index.html - view
• getting-started/index.html - view
• 1.x/contributing/index.html - view
• 1.x/core/index.html - view
• 1.x/deployment/index.html - view

There are more changes not included in the list