Update ReadTheDocs to align more with other Sumo repos look

[roywilly]

Issue

[Link to the issue resolved by this PR.]

Short description

Short description of the approach taken to solve the issue

Pre-review checklist

• Read through all changes. No redundant print() statements, commented-out code, or other remnants from the development. 👀
• Make sure tests pass after every commit. ✅
• New/refactored code is following same conventions as the rest of the code base. 🧬
• New/refactored code is tested. ⚙
• Documentation has been updated 🧾

Pre-merge checklist

• Commit history is consistent and clean. 👌

[equinor-ruaj]

👍