docs: fix table header

PR #99 was not enough.

documentation/hdf5-docs/registered_vol_connectors.md

@@ -15,8 +15,9 @@ Here is the current policy regarding VOL connector identifier assignment: Valid
 Please contact the maintainer of a VOL connector for help implementing the plugin.
 
 ## List of VOL Connectors Registered with The HDF Group
-| Connector | Connector Identifier | Search Name* | Short Description | URL  Contacts |
-| --- | --- | --- | --- | --- | ---| 
+
+| Connector | Connector Identifier | Search Name* | Short Description | URL | Contacts |
+| --- | --- | --- | --- | --- | --- | 
 | Asynchronous I/O | 512 | async | Provides support for asynchronous operations to HDF5 | [https://github.com/hpc-io/vol-async](https://github.com/hpc-io/vol-async) | Suren Byna (sbyna at lbl dot gov) |
 | Cache | 513 | cache | Provides support for multi-level, multi-location data caching to dataset I/O operations | [https://github.com/hpc-io/vol-cache](https://github.com/hpc-io/vol-cache) | Suren Byna (sbyna at lbl dot gov) |
 | Log-based | 514 | LOG | The log-based VOL plugin stores HDF5 datasets in a log-based storage layout.<br>In this layout, data of multiple write requests made by an MPI process are appended one after another in the file. Such I/O strategy can avoid the expensive inter-process communication and I/O serialization due to file lock contentions when storing data in the canonical order. Through the log-based VOL, existing HDF5 programs can achieve a better parallel write performance with minimal changes to their codes. | [https://github.com/DataLib-ECP/vol-log-based/blob/master/README.md](https://github.com/DataLib-ECP/vol-log-based/blob/master/README.md) | Kai Yuan Hou <br> (khl7265 at ece dot northwestern dot edu) |