Updated Intro to solana mobile

[dvrvsimi]

Problem

• Existing lesson doesn't account for error handling in the functions.
• Writing style in the existing lesson is redundant and doesn't totally follow the markdown specs in the contribution guideline.
• Flow diagrams in the existing lesson are old and not legible.
• A few grammar issues were found, old terminologies were used
• Code snippets were not optimally written in general

Summary of Changes

• Refactored .tsx sections to improve code readability
• Restructured markdown parts in compliance with the contribution guidelines provided
• Redesigned flow diagrams for better legibility and design
• Improved the overall tone to a more concise and beginner-friendly one

Fixes #