document behaviour of force-ignore on nested biome.json

src/content/docs/reference/configuration.mdx

@@ -120,13 +120,15 @@ also index source files if one or more rules from the
 [project domain](/linter/domains/#project) are enabled.
 
 The scanner respects both `files.includes` and the ignored patterns from
-`.gitignore` files, but there is one exception to be aware of: If any rule from
-the project domain is enabled, the scanner will index source files _including
-their dependencies_. This means that files that are ignored as part of
-`files.includes` may still get indexed by the scanner, as long as there is
-another included file that that imports those files. And this also means that
-`.d.ts` files and `package.json` manifests inside `node_modules/` may still get
-indexed too.
+`.gitignore` files, but there are two exceptions to be aware of:
+* Special files such as `biome.json` and `.gitignore` take priority over any
+  ignored patterns in `files.includes`.
+* If any rule from the project domain is enabled, the scanner will index source
+  files _including their dependencies_. This means that files that are ignored
+  as part of `files.includes` may still get indexed by the scanner, as long as
+  there is another included file that imports those files. And this also
+  means that `.d.ts` files and `package.json` manifests inside `node_modules/`
+  may still get indexed too.
 
 If you want to explicitly force some files to be ignored by the scanner, you can
 do so using a so-called _force-ignore pattern_. A force-ignore pattern looks
@@ -150,6 +152,9 @@ that indexing has any useful benefits. For folders containing generated files,
 we advise using regular ignore patterns so that type information can still be
 extracted from the files.
 
+For nested `biome.json` files as well as `.gitignore` files that you wish to
+explicitly ignore, the force-ignore syntax must also be used.
+
 ### `files.ignoreUnknown`
 
 If `true`, Biome won't emit diagnostics if it encounters files that it can't