Add an explanation note about AGPL in the context of enterprises (#677)

Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>

Author: jviotti

README.markdown

@@ -245,3 +245,17 @@ machine capabilities. If you desire to build a portable binary, or if the
 aggressive processor-specific optimisations cause any issues (we heard of some
 `Illegal instruction` cases), then configure the project with
 `-DJSONSCHEMA_PORTABLE:BOOL=ON`.
+
+License
+-------
+
+This project is released under the terms of the [GNU Affero General Public
+License v3.0](./LICENSE).
+
+**A note for enterprises:** Using the JSON Schema CLI during local development
+or as part of your CI/CD pipelines does not trigger the AGPL copyleft
+requirements. Your schemas, data, and surrounding code remain entirely yours.
+The copyleft provisions only apply if you modify the CLI source code itself or
+embed it within your own software. This is the same way that managing your
+proprietary code with [Git](https://git-scm.com) does not make your code
+subject to the [GPL](https://www.gnu.org/licenses/gpl-3.0.en.html).