docs: add essential documents for set-up, build procedure, and executing guides

[jaybxyz]

Description

This PR adopts documentation folder structure from cosmos-cash project and adds essential documents for how to set-up and build budgetd and how to use functions exist in the module.

closes: #28

Bullet Points

• add docs/Tutorials
  • init testnet with genesis setting for proposing budget(short voting period) and account balance for budget source accounts and collected budget accounts
  • add new budget plan sending a governance proposal ChangeParameterProposal
  • add a query to check balances of collection_address to see if the balances increase over time
• update README.md
• update TECHNICAL-SETUP.md

References

• cosmos-cash docs
• Admin: Documentation Structure #1

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Appropriate labels applied
• Targeted PR against correct branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes