Add support for an english version of the body campaign description

[slavcho]

Which area(s) of Podkrepi.bg are affected? (leave empty if unsure)

Campaigns

Describe the feature you'd like to request

Currently we support only one description of the campaign (title, text).
This causes problems with campaigns that are focused for a non BG audience.

Describe the solution you'd like

We need to support a second (english) description of the campaign.
It should be rendered when the language of the website is EN.

Describe alternatives you've considered

No response