Fix typo's en and improve language on MQTT data descriptions (#106165)

* Fix typo's en and prove language on MQTT data descriptions

* Update homeassistant/components/mqtt/strings.json

Co-authored-by: Joost Lekkerkerker <joostlek@outlook.com>

* Update homeassistant/components/mqtt/strings.json

* Update homeassistant/components/mqtt/strings.json

Co-authored-by: c0ffeeca7 <38767475+c0ffeeca7@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: c0ffeeca7 <38767475+c0ffeeca7@users.noreply.github.com>

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Co-authored-by: Joost Lekkerkerker <joostlek@outlook.com>
Co-authored-by: c0ffeeca7 <38767475+c0ffeeca7@users.noreply.github.com>