[Mime] Added getDispostion() to TextPart to get current content disposi…

[fabpot]

Q	A
Feature PR	symfony/symfony#49824
PR author(s)	@Cyb0rk
Merged in	6.3

We created this issue to not forget to document this new feature. We would really appreciate if you can help us with this task. If you are not sure how to do it, please ask us and we will help you.

To fix this issue, please create a PR against the 6.3 branch in the symfony-docs repository.

Thank you! 😃

[javiereguiluz]

I'm closing this as "won't document". It's a self-explanatory method that it's available just right where you need it, so developers will discover it via their IDE or text editor.