[$75 in kSQT] Add Graph Migration Docs for NEAR

[jamesbayly]

Extend our Graph Migration work to provide specific migration instructions and examples related to a NEAR project in specific ecosystems

Acceptance Criteria

• Migration guide code must be for NEAR
• There must be a real before and after example codebase (that is public and open source). You can migrate one of the examples here https://thegraph.com/docs/en/cookbook/near/#example-subgraphs
• This must be contributed as a PR to the documentation repo

From subquery/documentation#278

[web3cdnservices]

Docs for Near migration
subquery/documentation#385

Sources:
https://github.com/web3cdnservices/subquery-near-migration-from-thegraph-example

&&
Pull request. Bug into Near repo.

subquery/subql-near@main...web3cdnservices:subql-near-bugfixes:main////