Typo fixes in TTS docs.

[corbanmailloux]

Description:
This PR fixes a few documentation spelling errors in the TTS docs.

[mention-bot]

@corbanmailloux, thanks for your PR! By analyzing the history of the files in this pull request, we identified @Landrash, @balloob and @fabaff to be potential reviewers.

[fabaff]

Thanks 🐦

[Cooper-Dale]

the template is not working for me, I am using

data_template:
         message: "Temp is {{states('sensor.temp')}}"
         cache: false

and it works! Please check it out

[corbanmailloux]

@Cooper-Dale This is probably not the right place for your comment. If you are suggesting another change to these docs, please open a new pull request.