fix: properly allow for rootDir overriding

Author: chrisbbreuer

build.ts

@@ -11,6 +11,7 @@ const result = await Bun.build({
 
   plugins: [
     dts({
+      rootDir: `${import.meta.dir}/src`,
       cwd: import.meta.dir,
     }),
   ],

src/index.ts

@@ -27,7 +27,7 @@ export async function generate(entryPoints: string | string[], options?: DtsOpti
   const configJson = ts.readConfigFile(path, ts.sys.readFile).config
 
   const opts: TsOptions = {
-    rootDir: options?.cwd ?? process.cwd(),
+    rootDir: options?.rootDir ?? options?.cwd ?? process.cwd(),
     declaration: true,
     emitDeclarationOnly: true,
     noEmit: false,