fix(docs): fixed typo in import

Author: lexasq

libs/doc-pages/dropdown/src/lib/docs/usage.md

@@ -1,7 +1,7 @@
 ### Standalone component usage
 import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
 
-import { BsDropdownModule } from 'ngx-bootstrap/datepicker';
+import { BsDropdownModule } from 'ngx-bootstrap/dropdown';
 
 @Components({
   standalone: true,