Success Stories submission form - Add help text requesting Markdown formatting to the Content box

[loren-c]

Is your feature request related to a problem? Please describe.
When users use the Success Stories submission form to submit a success story, there is currently no guidance on whether to submit Success Stories in plain text or a mark up language. It's much faster on our end to post stories if they are submitted in Markdown so we don't have to format them ourselves.

Describe the solution you'd like
I'd like for there to be help text next to the Content text entry box on the Success Stories form indicating Markdown is preferred.

Describe alternatives you've considered
Currently we either reach out to request the submitter put their submission into Markdown after we receive it or we put it in Markdwown ourselves.

Additional context
Suggested text to add to the Success Stories submission form is:
"Submissions in Markdown are strongly preferred and can be processed more quickly" as shown in the attached screenshot in red.
(I'm not 100% sure that wording is the accurate way to describe text being "in Markdown"; please edit if it doesn't quite make sense as I've written it. Thank you!)

@ewdurbin

[JacobCoffee]

first glance: I believe this would be done in or around

pythondotorg/successstories/forms.py

Line 9 in a3719ef

class StoryForm(ContentManageableModelForm):