Update README.md and LICENSE

- strip needless executable permissions from both files
- fix markdownlint-cli errors of README.md
- append info java binar is needed to run

Author: eggplants

LICENSE

@@ -1,19 +1,29 @@
 # OpenApi Generator PIP Package Generator
 
-[![Join the Slack chat room](https://img.shields.io/badge/Slack-Join%20the%20chat%20room-orange)](https://join.slack.com/t/openapi-generator/shared_invite/zt-12jxxd7p2-XUeQM~4pzsU9x~eGLQqX2g)
-<a href="https://github.com/psf/black"><img alt="Code style: black" src="https://img.shields.io/badge/code%20style-black-000000.svg"></a>
-
-OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and 
-configuration automatically given an OpenAPI Spec (both 2.0 and 3.0 are supported). Please see
-[OpenAPITools/openapi-generator](https://github.com/OpenAPITools/openapi-generator)
+[![Join the Slack chat room](
+  <https://img.shields.io/badge/Slack-Join%20the%20chat%20room-orange>
+)](
+  <https://join.slack.com/t/openapi-generator/shared_invite/zt-12jxxd7p2-XUeQM~4pzsU9x~eGLQqX2g>
+) [![Code style: black](
+  <https://img.shields.io/badge/code%20style-black-000000.svg>
+)](
+  <https://github.com/psf/black>
+) [![Ruff](
+  <https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/ruff/main/assets/badge/v2.json>
+)](
+  <https://github.com/astral-sh/ruff>
+)
+
+OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and configuration automatically given an OpenAPI Spec (both 2.0 and 3.0 are supported). Please see [OpenAPITools/openapi-generator]
 
 ---
 
-This project checks the [maven repository](https://mvnrepository.com/artifact/org.openapitools/openapi-generator-cli) 
-once a day for a new version and will publish this new version automatically as a python package.
+This project checks the [maven repository] once a day for a new version and will publish this new version automatically as a python package.
 
 ## Installation
 
+You must have the `java` binary executable available on your PATH for this to work. (JDK 11 is the minimal version supported. To install OpenJDK, please visit <https://adoptium.net/>)
+
 You can install the package either in a virtual environment or globally.
 
 ```sh
@@ -24,8 +34,7 @@ pip install openapi-generator-cli
 pip install openapi-generator-cli==4.3.1
 ```
 
-After installation `openapi-generator` command will be available in your virtual environment or globally 
-depending on your installation
+After installation `openapi-generator` command will be available in your virtual environment or globally depending on your installation.
 
 To check the version, for example. Type the following command
 
@@ -36,8 +45,7 @@ openapi-generator version
 
 ## Further Documentation
 
-Please refer to the [official openapi-generator docs](https://github.com/OpenAPITools/openapi-generator#3---usage) for
-more information about the possible arguments and a detailed usage manual of the command line interface.
+Please refer to the [official openapi-generator docs] for more information about the possible arguments and a detailed usage manual of the command line interface.
 
 ## Like the package?
 
@@ -46,3 +54,7 @@ Please leave a star.
 ## Have suggestions or feedback?
 
 Please raise an issue, happy to hear from you :)
+
+[OpenAPITools/openapi-generator]: <https://github.com/OpenAPITools/openapi-generator>
+[maven repository]: <https://mvnrepository.com/artifact/org.openapitools/openapi-generator-cli>
+[official openapi-generator docs]: <https://github.com/OpenAPITools/openapi-generator#3---usage>