ENH: Make the documentation build be permissive with warnings (#66)

* DOC: Remove unnecessary indentation in package TOC entry

Remove unnecessary indentation in package TOC entry. Allows the package
to be rendered.

Fixes:
```
/home/runner/work/tract_querier/tract_querier/doc/index.rst:23:
 WARNING: toctree contains reference to nonexisting document ' tract_querier' [toc.not_readable]
```

raised for example in:
https://github.com/demianw/tract_querier/actions/runs/12247250821/job/34164730870#step:4:53

* DOC: Miscellaneous style improvements to documentation index file

Miscellaneous style improvements to documentation index file:
- Remove unnecessary empty lines: Sphinx does not take them into account
  anyways.
- Make the documentation index header punctuation character length match
  the header lenght.

* ENH: Make the documentation build be permissive with warnings

Make the documentation build be permissive with warnings: remove the `W`
flag to avoid treating warnings as errors.

Warnings will still be reported in the GHA workflow build log.

.github/workflows/doc_build.yaml

@@ -28,4 +28,4 @@ jobs:
 
     - name: Build docs
       run: |
-          make -C doc/ SPHINXOPTS="-W -v" BUILDDIR="$HOME/docs" OUTDIR="$HOME/html" html
+          make -C doc/ SPHINXOPTS="-v" BUILDDIR="$HOME/docs" OUTDIR="$HOME/html" html

doc/index.rst

@@ -4,7 +4,7 @@
    contain the root `toctree` directive.
 
 Welcome to WMQL's documentation!
-=========================================
+================================
 
 The White Matter Query Language (WMQL) is a technique to formally describe white matter tracts and to automatically extract them from diffusion MRI volumes. This query language allows us to construct a dictionary of anatomical definitions describing white matter tracts. The definitions include adjacent gray and white matter regions, and rules for spatial relations. This enables the encoding of anatomical knowledge of the human brain white matter as well as the automated coherent labeling of white matter anatomy across subjects.
 
@@ -17,16 +17,10 @@ Click here for :ref:`example_script`
 
 This software is published under the following :ref:`license`
 
-
-
-
 .. toctree::
    :maxdepth: 1
 
-    tract_querier
-
-
-
+   tract_querier
 
 Indices and tables
 ==================
@@ -35,7 +29,6 @@ Indices and tables
 * :ref:`modindex`
 * :ref:`search`
 
-
 .. rubric:: Footnotes
 
 .. [#f1] Self archived author version available for download `here <https://hal.inria.fr/hal-01247061/document>`_. The previously published conference article can be found here `"On Describing Human White Matter Anatomy: The White Matter Query Language", Wassermann et al., MICCAI 2013 <_static/WassermannMICCAI2013.pdf>`_.