Add introduction to the Abstract SDK

[CyberHoward]

Also:

• Rename sdk api Vault to Accountant to signify the functionality of the API.
• Add a withdraw function to Bank
• Add a lot of doc-comments
• Fix a left over Os reference

[codecov]

Codecov Report

Merging #340 (9c8c781) into main (b0f0673) will decrease coverage by 0.1%.
The diff coverage is 14.2%.

Impacted Files	Coverage Δ
contracts/account/manager/src/commands.rs	94.9% <ø> (ø)
contracts/native/account-factory/src/commands.rs	93.0% <ø> (ø)
contracts/native/ans-host/src/queries.rs	94.1% <ø> (ø)
contracts/native/ibc-client/src/commands.rs	58.0% <ø> (ø)
contracts/native/version-control/src/commands.rs	97.4% <ø> (ø)
packages/abstract-adapter/src/endpoints/execute.rs	92.3% <ø> (ø)
packages/abstract-app/src/endpoints/instantiate.rs	94.0% <ø> (ø)
packages/abstract-sdk/src/ans_resolve.rs	94.5% <ø> (ø)
packages/abstract-sdk/src/apis/accounting.rs	0.0% <0.0%> (ø)
packages/abstract-sdk/src/apis/adapter.rs	99.0% <ø> (ø)
... and 22 more