docs: point SDK source links to official repos

[newmattock]

Summary

• Update the source package repository field from the old personal namespace to BitgesellOfficial/bitgesell-blockchain-sdk.
• Update the README documentation link from the stale personal GitHub Pages URL to the official BitgesellOfficial/bitgesell-blockchain-sdk-docs repository.

Verification

• rg -n "naftalimurgor/bitgesell-blockchain-sdk|naftalimurgor.github.io/bitgesell-blockchain-sdk" README.md package.json package-lock.json; test $? -eq 1
• node -e "JSON.parse(require('fs').readFileSync('package.json','utf8')); JSON.parse(require('fs').readFileSync('package-lock.json','utf8')); console.log('json ok')"
• gh repo view BitgesellOfficial/bitgesell-blockchain-sdk --json url,nameWithOwner
• gh repo view BitgesellOfficial/bitgesell-blockchain-sdk-docs --json url,nameWithOwner
• git diff --check

Bounty context

Submitted for Bitgesell improvement bounty consideration: BitgesellOfficial/bitgesell#39.

[MyTH-zyxeon]

Maintainer review note for the #81/#39 improvement queue:

I checked head a8fce6b: this is a small docs/package metadata cleanup, and the target repos exist. BitgesellOfficial/bitgesell-blockchain-sdk and BitgesellOfficial/bitgesell-blockchain-sdk-docs both resolve, the decoded README no longer carries the old naftalimurgor.github.io docs URL, and package.json now points its repository at the official SDK repo.

Acceptance checks:

• Render the README once and confirm the new GitHub docs-repo link is the intended user destination rather than the old GitHub Pages site.
• Keep the corrected trailing newline in README so future docs diffs stay clean.
• Consider fixing the existing documenation typo while this line is being touched, unless the maintainer wants strictly link-only scope.
• Run the package JSON parse check from the PR body before merge; no dependency install or runtime build should be needed for this metadata-only change.

No wallet/key/node/live-chain scope; this is docs/package hygiene only.