Update Docs to match Sprinter Website Rebrand

[alexmmueller]

Overview

We are launching rebranded website soon and need to update our docs to include the new narrative, hints on upcoming V2 etc.

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Acceptance Criteria

Update Navigation

• Introduce new Section 'Stash Credit (V2)'
• Rename 'Sprinter Stash" section to 'Stash Solver Credit (V1)' and move section after 'Stash Credit (V2)'
• Remove section 'Sprinter Solve'

Update Copy

• Replace copy in 'What is Sprinter?' section with copy here
• Add copy to 'Stash Credit (V2)' section from here

Update Glossary

• Update glossary to include more general credit terms versus pure solving