[FIX] subscriptions: updated and corrected mistake re: eLearning

[ksc-odoo]

PROJECT TASK: https://www.odoo.com/web#id=3811470&cids=3&model=project.task&view_type=form

• fixed issue regarding eLearning, product variants, and recurring prices
• updated the doc with new screenshots and more accurate process

[robodoo]

Pull request status dashboard.

[ksc-odoo]

Hey there @Felicious -- this one is ready for a Peer Review from you whenever you get a chance. Thanks! 🙏

[ksc-odoo]

Thank you for the always helpful feedback, @Felicious -- i made the necessary modifications, and believe this one is now ready for Tech Review from you, @samueljlieber -- whenever you get a chance! Thanks! 🙏