Clarify that APCu may be the easiest option, and add basic instructions?

Problem/Motivation

Since APCu might already be available, it could be the easiest option, whereas installing Drupal Redis → requires a few steps.

Steps to reproduce

Proposed resolution

Clarify that APCu is probably the easiest option, by adding something like this in the README?

You may already have APCu installed. Check PHP status and /admin/reports/status for these lines:

PHP APCu available caching: Memory available: 98.23 MB.
PHP APCu caching: Enabled (128 MB)

To give APCu more memory, add this in /etc/php/8.4/apache2/php.ini (for PHP 8.4) and restart the server:

# More memory for APCu
apc.shm_size = 256M

Remaining tasks

User interface changes

API changes

Data model changes