Docs: Fix Link Format (#710)

Fix an ill-formatted .rst link

Author: ax3l

Docs/source/running_cpp/parameters.rst

@@ -997,7 +997,7 @@ Diagnostics and output
 
 * ``warpx.openpmd_backend`` (``bp``, ``h5`` or ``json``) optional
     `I/O backend <https://openpmd-api.readthedocs.io/en/latest/backends/overview.html>`_ for `openPMD <https://www.openPMD.org>`_ data dumps.
-    ``bp`` is the `ADIOS I/O library <https://csmd.ornl.gov/adios>`_, ``h5`` is the `HDF5 format <https://www.hdfgroup.org/solutions/hdf5/>`, and ``json`` is a `simple text format <https://en.wikipedia.org/wiki/JSON>`_.
+    ``bp`` is the `ADIOS I/O library <https://csmd.ornl.gov/adios>`_, ``h5`` is the `HDF5 format <https://www.hdfgroup.org/solutions/hdf5/>`_, and ``json`` is a `simple text format <https://en.wikipedia.org/wiki/JSON>`_.
     ``json`` only works with serial/single-rank jobs.
     When WarpX is compiled with openPMD support, the first available backend in the order given above is taken.