Update installation.rst to fix typo in a note.

doc/source/installation.rst

@@ -158,12 +158,12 @@ Once that's finished, you can enter the container in writable mode to install Gs
 
    .. code:: bash
 
-       $ singularity run --writable -B /cvmfs gstlal-dev
+       $ singularity run --writable gstlal-dev
        WARNING: By using --writable, Singularity can't create /cvmfs destination automatically without overlay or underlay
        FATAL:   container creation failed: mount /cvmfs->/cvmfs error: while mounting /cvmfs: destination /cvmfs doesn't exist in container
 
    In this case, one way to resolve this error is to add directories in the
-   container for each of the bind mounts explicitly:
+   container for each of the bind mounts explicitly, e.g.,:
 
    .. code:: bash