docs: documentation updates for v1.20

[shahednasser]

• Added upgrade guide for v1.20 + for stripe plugin's v6.0.7
• Added new admin languages to list of languages
• Added details about stripe's webhook environment variables.
• Small fixes to pricing TSDocs

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
api-reference	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jan 9, 2024 5:39pm
docs-ui	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jan 9, 2024 5:39pm
medusa-dashboard	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jan 9, 2024 5:39pm
medusa-docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jan 9, 2024 5:39pm

[changeset-bot]

⚠️ No Changeset found

Latest commit: 316e75a

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR