Add description for PR #6858

[mSapik]

Description:

Description for PR #6858 "Add Mitsubishi Heavy Industries as climate IR in ESPhome Mitsubishi Heavy SRKxxZJ-S (remote control P/N RKX502A001C) with receiver support."

Related issue (if applicable): fixes

Pull request in esphome with YAML changes (if applicable): esphome/esphome#6858

Checklist:

• [x] I am merging into next because this is new documentation that has a matching pull-request in esphome as linked above.
  or

• [ ] I am merging into current because this is a fix, change and/or adjustment in the current documentation and is not for a new component or feature.

• [ ] Link added in /index.rst when creating new documents for new components or cookbook.