Fix code block indentation in docs

[dereuromark]

Summary

Fixes PHP code block indentation in top-level code examples that used incorrect 8- or 12-space indentation instead of the CakePHP standard 4-space convention.

Note: Only top-level code blocks were affected. Code inside class method bodies (where 12-space = 8 base + 4 chain) was already correct and left unchanged.

Files fixed:

• core-libraries/email.md — Mailer chained calls at top level had 12-space indent → fixed to 4 (with 8 for nested viewBuilder() chains)
• core-libraries/collections.md — ->map() chain and TotalOrderCalculator class body had 8-space indent → fixed to 4
• controllers.md — fetchTable()->find() arguments had 8-space indent → fixed to 4
• orm/associations.md — Array arguments in belongsTo(), hasMany(), hasOne() had 16-space indent → fixed to 12 (inside method body)
• orm/retrieving-data-and-resultsets.md — find('list', arguments had 8-space indent → fixed to 4, added trailing comma