Update README with steps to update license list

Update the README with steps to update license list so community members can easily update the license list on behalf of the maintainers.

Signed-off-by: Steven Buccini <[email protected]>

Author: stevenbuccini

README.md

@@ -48,6 +48,15 @@ the CycloneDX version supported by the target system.
 
 The library API documentation can be viewed online at [https://cyclonedx.github.io/cyclonedx-core-java/](https://cyclonedx.github.io/cyclonedx-core-java/).
 
+## Updating the license list
+1. Download the latest tagged release from [this repo](https://github.com/spdx/license-list-data/tags).
+2. Extract the archived directory.
+3. Navigate to the `license-list-vX.X.X/text/` directory.
+4. Copy all licenses from that directory to the `src/main/java/resources/licenses/` directory in this repo.
+5. Copy `license-list-vX.X.X/json/licenses.json` into the `src/main/java/resources/licenses/` directory in this repo.
+6. Download [this file](http://cyclonedx.org/schema/spdx.schema.json) (ex: `curl http://cyclonedx.org/schema/spdx.schema.json -o spdx.schema.json`). The `$comment` field should match the version you donwloaded from GitHub. Copy this file into `src/main/resources/`.
+7. Download [this file](https://cyclonedx.org/schema/spdx.xsd) (ex `curl https://cyclonedx.org/schema/spdx.xsd -o spdx.xsd`). The version field should match the version you donwloaded from GitHub. Copy this file into `src/main/resources/`. 
+
 Copyright & License
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