Infrastructure and documentation fixes for post-1.0 release

What's Changed

• Update for NiFi-2.6.0 by @Chaffelson in #391

Infrastructure Fixes

• ReadTheDocs configuration: Fixed .readthedocs.yaml to properly install package with docs extras, ensuring setuptools-scm is available for dynamic version detection. Stable docs now display correct version instead of 0.19.
• Pylint 3.x compatibility: Updated pylintrc with ignore-paths regex patterns to properly exclude generated code directories (nipyapi/nifi/, nipyapi/registry/, _version.py) in CI environments using pylint 3.x.
• CI workflow optimization: Reordered GitHub Actions steps to upload coverage reports before make test-dist runs, preventing make clean from deleting coverage.xml before codecov upload.

Documentation Updates

• Branch references: Updated all documentation links from NiFi2x development branch to main default branch (README badges, contribution guide links, Sphinx source code references).
• LICENSE: Added full Apache 2.0 license text to repository root.
• Development workflow: Added .cursor/ to .gitignore for IDE-specific files.

Full Changelog: v1.0.0...v1.0.1