feat: add processing overview

[Kaladin13]

Closes #699

[github-actions]

LGTM

[github-actions]

To fix the formatting issues:

1. Install necessary dependencies: npm ci
2. Then, run this command:

npx remark -o --silent --silently-ignore payments/jettons.mdx payments/overview.mdx payments/toncoin.mdx 

[github-actions]

To fix the formatting issues:

1. Install necessary dependencies: npm ci
2. Then, run this command:

npx remark -o --silent --silently-ignore payments/jettons.mdx payments/overview.mdx payments/toncoin.mdx 

[github-actions]

To fix the formatting issues:

1. Install necessary dependencies: npm ci
2. Then, run this command:

npx remark -o --silent --silently-ignore payments/jettons.mdx payments/overview.mdx payments/toncoin.mdx 

[github-actions]

To fix the formatting issues:

1. Install necessary dependencies: npm ci
2. Then, run this command:

npx remark -o --silent --silently-ignore payments/jettons.mdx payments/overview.mdx payments/toncoin.mdx 

.