Update arxiv.py

pygetpapers/repository/arxiv.py

@@ -50,7 +50,17 @@
 from pygetpapers.repositoryinterface import RepositoryInterface
 
 class Arxiv(RepositoryInterface):
-    """Arxiv class which handles arxiv repository"""
+    ""arxiv.org repository
+
+    This uses a PyPI code `arxiv` to download metadata. It is not clear whether this is 
+    created by the `arXiv` project or layered on top of the public API. 
+
+    `arXiv` current practice for bulk data download (e.g. PDFs) is described in
+https://arxiv.org/help/bulk_data. Please be considerate and also include a rate limit.
+
+
+
+    """
 
     def __init__(self):
         self.download_tools = DownloadTools(ARXIV)
@@ -176,4 +186,4 @@ def apipaperdownload(self, query_namespace):
             makecsv=query_namespace["makecsv"],
             makexml=query_namespace["xml"],
             makehtml=query_namespace["makehtml"],
-        )   
+        )