Update Readme Configuration Issues

[cutaway]

A few recommendations that would have saved me some time.

Please add a comment about the MISP admin account password (MISP_ADMIN_PASSPHRASE) requirements. If the password does not match these requirements the user will have to update the account using the "cake" utility. This should help users during initial configuration and testing.

• Six (6) characters long
• One upper
• One lower
• One digit or special character

Update the "MISP_BASEURL" parameter in "env.txt" to be "https://" instead of "http://". Adding the "s" might seem trivial but it is easy to miss and this instance has already been set up for encryption of the admin portal communications.

Thank you, cutaway