Fix opds2 -> pyopds2 statement in README example

Author: mekarpeles

README.md

@@ -27,7 +27,7 @@ To use this library, you must implement two key classes:
 ### Example
 
 ```python
-from opds2 import Catalog, DataProvider, DataProviderRecord, Metadata, Link, SearchResponse
+from pyopds2 import Catalog, DataProvider, DataProviderRecord, Metadata, Link, SearchResponse
 
 class MyRecord(DataProviderRecord):
     def metadata(self):
@@ -73,4 +73,4 @@ This library was inspired by [The Palace Project's OPDS implementation](https://
 
 ## License
 
-AGPLv3 License. See `LICENSE` for details.
+AGPLv3 License. See `LICENSE` for details.