eslint-plugin: add doc rule links and update README

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/eslint-plugin/README.md

@@ -35,6 +35,8 @@ rules: {
 
 The following rules are provided by this plugin:
 
-| Rule                                      | Description                                                                     |
-| ----------------------------------------- | ------------------------------------------------------------------------------- |
-| `@backstage/no-forbidden-package-imports` | Disallow internal monorepo imports from package subpaths that are not exported. |
+| Rule                                                                                    | Description                                                                                                              |
+| --------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ |
+| [@backstage/no-forbidden-package-imports](./docs/rules/no-forbidden-package-imports.md) | Disallow internal monorepo imports from package subpaths that are not exported.                                          |
+| [@backstage/no-relative-monorepo-imports](./docs/rules/no-relative-monorepo-imports.md) | Forbid relative imports that reach outside of the package in a monorepo.                                                 |
+| [@backstage/no-undeclared-imports](./docs/rules/no-undeclared-imports.md)               | Forbid imports of external packages that have not been declared in the appropriate dependencies field in `package.json`. |

packages/eslint-plugin/rules/no-forbidden-package-imports.js

@@ -25,6 +25,11 @@ module.exports = {
     messages: {
       forbidden: '{{packageName}} does not export {{subPath}}',
     },
+    docs: {
+      description:
+        'Disallow internal monorepo imports from package subpaths that are not exported.',
+      url: 'https://github.com/backstage/backstage/blob/master/packages/eslint-plugin/docs/rules/no-forbidden-package-imports.md',
+    },
   },
   create(context) {
     return visitImports(context, (node, imp) => {

packages/eslint-plugin/rules/no-relative-monorepo-imports.js

@@ -29,6 +29,11 @@ module.exports = {
       forbidden:
         "Relative imports of monorepo packages are forbidden, use '{{newImport}}' instead",
     },
+    docs: {
+      description:
+        'Forbid relative imports that reach outside of the package in a monorepo.',
+      url: 'https://github.com/backstage/backstage/blob/master/packages/eslint-plugin/docs/rules/no-relative-monorepo-imports.md',
+    },
   },
   create(context) {
     const packages = getPackageMap(context.getCwd());

packages/eslint-plugin/rules/no-undeclared-imports.js

@@ -125,6 +125,11 @@ module.exports = {
       switch:
         '{{ packageName }} is declared in {{ oldDepsField }}, but should be moved to {{ depsField }} in {{ packageJsonPath }}.',
     },
+    docs: {
+      description:
+        'Forbid imports of external packages that have not been declared in the appropriate dependencies field in `package.json`.',
+      url: 'https://github.com/backstage/backstage/blob/master/packages/eslint-plugin/docs/rules/no-undeclared-imports.md',
+    },
   },
   create(context) {
     const packages = getPackageMap(context.getCwd());