Docs: advise against caching AR objects
Docs: advise against caching AR objects

Based on this comment https://github.com/rails/rails/issues/43767#issuecomment-1000988644

Closes https://github.com/rails/rails/issues/43767

kmcphillips/rails,rails/rails,rails/rails,kddeisz/rails,MSP-Greg/rails,rails/rails,MSP-Greg/rails,esparta/rails,yahonda/rails,BlakeWilliams/rails,yahonda/rails,yawboakye/rails,kddeisz/rails,georgeclaghorn/rails,kmcphillips/rails,kddeisz/rails,Erol/rails,yawboakye/rails,rails/rails,kmcphillips/rails,Edouard-chin/rails,esparta/rails,Edouard-chin/rails,BlakeWilliams/rails,yahonda/rails,MSP-Greg/rails,Erol/rails,Edouard-chin/rails,Edouard-chin/rails,kddeisz/rails,georgeclaghorn/rails,yawboakye/rails,BlakeWilliams/rails,georgeclaghorn/rails,esparta/rails,esparta/rails,yawboakye/rails,Erol/rails,yahonda/rails,MSP-Greg/rails,georgeclaghorn/rails,Erol/rails,BlakeWilliams/rails,kmcphillips/rails