Add documentation for commit title conventions

Since we enforce commit title conventions in our PRs to create parts of the release notes automatically we need to publish the documentation of our conventions in the open.

We currently work on general structures (like `CONTRIBUTIONS.md`, ...) and therefore the documentation should be added first in a separate file or postponed until we have finished all the general work.

The doc should contain the following table:

The following prefixes should be used for the types of changes indicated. In general prefer the first item from this table that matches the change to be committed.

Prefix | Meaning and examples
-- | --
feat | Changes to enable or support a new featureExamples:Make shadowgraph compatible with birth roundsImplement HIP-796 Operation PrimitivesCreate an ISS detector component
fix | Changes to resolve or remediate a bug or risk itemExamples:Fixing a null pointer exception found in testnetCleaning up MinGenInfo serialization to add a size limitFixing defects found in differential testing
test | Changes that only affect test code, add or remove tests, or fix testing issuesExamples:Enable fuzzy matching for TraceabilitySuiteAdd a comprehensive unit test for KeyComparatorRemove usage of snapshotMode in HAPI tests
refactor | Changes that reorganize the code without changing functionalityExamples:Changing the package name of a metrics libraryRenaming a class to fix a typo in the namerefactor to remove dependencies to contractMustBePresent
perf | Changes that improve performance without changing functionalityExamples:Replacing a synchronized map with a concurrent mapimprove virtual hashing performanceAdding “cache warming” support to improve virtual map performance.
docs | Changes to create, modify, or improve documentationExamples:Add sonar quickstartAdd first logging documentationCreate command to generate a legend for framework diagrams
build | Changes affecting the build system only, or updating external dependencies.Examples:Update develop to use add-pbj-types-for-state (change to build definition)Bump google-github-actions/upload-cloud-storage from 1.0.3 to 2.1.0Update local-node Docker images to Java 21
ci | Changes to configuration files and scripts for the continuous integration environment.Examples:adding tool configuration files to support codacy reportingensure validation runners use the same docker & containerd versions
style | Changes that fix stylistic issues and do not change functionalityExamples:Improve ugly html (in a CLI logging output class).
chore | Changes that do not fit in any other category. This should be rarely used.Examples:Cherry-pick commit to release branch