SDS: add missing docstrings

obspy/clients/filesystem/sds.py

@@ -81,6 +81,22 @@ def __init__(self, sds_root, sds_type="D", format="MSEED",
             supported by ObsPy. Usually, SDS archives are stored in "MSEED"
             format. Can be set to `None` for file format autodetection (slowing
             down the reading).
+        :type fileborder_seconds: float
+        :param fileborder_seconds: Defines in which cases the client checks the
+            previous/next daily file for the requested data (data in SDS
+            archives usually spill over on the day break, at least for a few
+            seconds). For example setting `fileborder_seconds=30` means that
+            for a request with `starttime` at `00:00:29` UTC (or an `endtime`
+            at `23:59:31`), the previous daily file is also checked, if it
+            contains matching data. The maximum of both `fileborder_seconds`
+            and `fileborder_samples` is used when determining if previous/next
+            day should be checked for data.
+        :type fileborder_samples: int
+        :param fileborder_samples: Similar to `fileborder_seconds`. The given
+            number of samples is converted to seconds by mapping the band
+            code of the requested channel to sampling frequency. The maximum of
+            both `fileborder_seconds` and `fileborder_samples` is used when
+            determining if previous/next day should be checked for data.
         """
         if not os.path.isdir(sds_root):
             msg = ("SDS root is not a local directory: " + sds_root)