DOC: Emphasise that package name contains hyphens; some formatting fixes

The fsl-sub conda package has been renamed from fsl_sub to fsl-sub for parity with the PyPi and conda-forge releases. This is an annoying constraint of publishing to PyPi - it automatically converts underscores to hyphens.

INSTALL.md

@@ -33,10 +33,10 @@ conda create -n fsl_sub python=3
 source activate fsl_sub
 ~~~
 
-and install fsl_sub with:
+and install fsl\_sub with the following (note that the package names are delimited with hyphens and not underscores):
 
 ~~~bash
-conda install -c https://fsl.fmrib.ox.ac.uk/fsldownloads/fslconda/public -c conda-forge fsl_sub
+conda install -c https://fsl.fmrib.ox.ac.uk/fsldownloads/fslconda/public -c conda-forge fsl-sub
 ~~~
 
 Plugins can be installed with:
@@ -44,13 +44,13 @@ Plugins can be installed with:
 Grid Engine...
 
 ~~~bash
-conda install -c https://fsl.fmrib.ox.ac.uk/fsldownloads/fslconda/public -c conda-forge fsl_sub_plugin_sge
+conda install -c https://fsl.fmrib.ox.ac.uk/fsldownloads/fslconda/public -c conda-forge fsl-sub-plugin-sge
 ~~~
 
 SLURM...
 
 ~~~bash
-conda install -c https://fsl.fmrib.ox.ac.uk/fsldownloads/fslconda/public -c conda-forge fsl_sub_plugin_slurm
+conda install -c https://fsl.fmrib.ox.ac.uk/fsldownloads/fslconda/public -c conda-forge fsl-sub-plugin-slurm
 ~~~
 
 ### Installation in a virtual environment