DOC: Add IndiScale-specific explanations to README.md

README.md

 @indiscale/ckeditor5-complexitywiki-plugins
 ===========================================
 
-This package was created by the [ckeditor5-package-generator](https://www.npmjs.com/package/ckeditor5-package-generator) package.
+This plugin troduces three buttons that insert specific syntax used for CaosDB's
+wiki app into the editor field:
+
+* An `inlineMathButton` which inserts the delimiters for inline MathJax at the
+  position of the cursor.
+* A `displayMathButton` which inserts the delimiters for display MathJax at the
+  position of the cursor.
+* An `inlineReferenceButton` which inserts a template for an inline reference to
+  another CaosDB entity or one of its properties at the position of the cursor.
+
+This package was created by the
+[ckeditor5-package-generator](https://www.npmjs.com/package/ckeditor5-package-generator)
+package.
 
 ## Table of contents
 
@@ -20,7 +32,27 @@ This package was created by the [ckeditor5-package-generator](https://www.npmjs.
 
 ## Developing the package
 
-To read about the CKEditor 5 framework, visit the [CKEditor5 documentation](https://ckeditor.com/docs/ckeditor5/latest/framework/index.html).
+To develop this package, edit the code in the `src` directory. You can use the
+[`npm run start` script](#start) to test your changes directly with the editor
+defined in `sample/ckeditor.js`. To actually test it together with CaosDB's web
+interface, the following steps have to be followed:
+
+1. `npm pack` this repository and install it in the `ckeditor5-build-classic`
+   package of our [CKeditor 5
+   fork](https://gitlab.indiscale.com/caosdb/src/ckeditor5).
+2. Test and build the package as described in that repo's `README_INDISCALE.md`.
+3. Zip and copy the build files to `caosdb-webui/libs`
+4. Start a CaosDB server with that version of the webinterface and test the
+   editor in the edit mode
+
+Only after successful tests and a code review of your changes in this
+repository, merge your development branch and publish the new version of this
+repo on npm with `npm publish`. Then it can be included in our custom build of
+CKEditor which then can subsequently be used in the upstream repo of the
+caosdb-webui.
+
+To read about the CKEditor 5 framework, visit the [CKEditor5
+documentation](https://ckeditor.com/docs/ckeditor5/latest/framework/index.html).
 
 ## Available scripts
 
@@ -81,6 +113,18 @@ Examples:
 npm run lint
 ```
 
+### `lint-fix`
+
+Like the above [`lint`](#lint) but runs ESLint with the `--fix` option which
+fixes a lot of formatting issues automatically.
+
+Examples:
+
+```bash
+# Execute eslint with --fix option
+npm run lint-fix
+```
+
 ### `stylelint`
 
 Similar to the `lint` task, stylelint analyzes the CSS code (`*.css` files in the `theme/` directory) in the package.