NIFI-13909 Refresh and Streamline Project README

[exceptionfactory]

Summary

NIFI-13909 Updates and simplifies the primary project README.md with additional badges and streamlined command examples.

Additional badges include the following:

• nifi-api link to Maven Central
• javadoc link to Javadocs for nifi-api with latest version
• license indicator with Apache-2.0 based on GitHub project LICENSE declaration
• issues link to Apache Jira
• contact links to Developers and Users mailing lists
• follow link to LinkedIn page
• follow link to X

Many of the badges include logo icons, and project colors in some cases.

The refreshed Features section highlights Python Processors and single sign-on, among others.

Instead of including separate build information for MiNiFi and Registry, the new Projects section has links to the README.md files for these projects.

The Developing and Running sections are streamlined to avoid unnecessary directory and version information, retaining the commands to run.

The Documentation and Getting Help sections are removed, now covered under additional project badges.

The Export Control section retains the previous wording, but contains an updated list of linked libraries and frameworks that provide encrypted communication and storage capabilities.

Viewing the source branch for this pull request displays the rendered version of the README.md

Tracking

Please complete the following tracking steps prior to pull request creation.

Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

• Pull Request title starts with Apache NiFi Jira issue number, such as NIFI-00000
• Pull Request commit message starts with Apache NiFi Jira issue number, as such NIFI-00000

Pull Request Formatting

• Pull Request based on current revision of the main branch
• Pull Request refers to a feature branch with one commit containing changes

Verification

Please indicate the verification steps performed prior to pull request creation.

Build

• Build completed using mvn clean install -P contrib-check
  • JDK 21

Licensing

• New dependencies are compatible with the Apache License 2.0 according to the License Policy
• New dependencies are documented in applicable LICENSE and NOTICE files

Documentation

• Documentation formatting appears as expected in rendered files

[EndzeitBegins]

Looks good, thank you for the adjustments @exceptionfactory. 👍🏻

[ChrisSamo632]

What do you think about including the nifi maven plugin here too, as that's a separate project upon which nifi build depends?