Resolve warnings showing

[ramereth]

The following warnings are showing that need to be resolved:

• Server has no maintenance window start time configured. This means resource intensive daily background jobs will also be executed during your main usage time. We recommend to set it to a time of low usage, so users are less impacted by the load caused from these heavy tasks. For more details see the documentation ↗.
• The PHP OPcache module is not properly configured. The OPcache interned strings buffer is nearly full. To assure that repeating strings can be effectively cached, it is recommended to apply "opcache.interned_strings_buffer" to your PHP configuration with a value higher than "8".. For more details see the documentation ↗.
• The "Strict-Transport-Security" HTTP header is not set to at least "15552000" seconds. For enhanced security, it is recommended to enable HSTS as described in the security tips ↗.
• Your web server is not properly set up to resolve "/.well-known/caldav". Further information can be found in the documentation ↗.
• Your web server is not properly set up to resolve "/.well-known/carddav". Further information can be found in the documentation ↗.
• The database is used for transactional file locking. To enhance performance, please configure memcache, if available. For more details see the documentation ↗.