Add info on theories that are unavailable to docs

doc/sphinx/source/theory/theoryindex.rst

@@ -1,8 +1,15 @@
+.. _theory-indexes:
+
 Theory indexes
 ==============
 
-In the table below you can see explicit content of the
-``TheoryIndex`` table from the ``theory.db`` file.
+In the table below you can see explicit content of the ``TheoryIndex`` table
+from the ``theory.db`` file. Note that not every theory listed in the database
+is available to be downloaded from the :ref:`NNPDF-server`. In particular,
+theories that are outdated are not stored on the server, but their settings will
+remain in the database. To find a list of the theories that are available on the
+server, one can use the vp-list script (see :ref:`vp-list`) as so: :code:`vp-
+list -r theories`.
 
 .. csv-table:: theory.db
    :file: ../theories.csv

doc/sphinx/source/theory/theoryparamsinfo.md

@@ -1,8 +1,9 @@
 # Looking up the parameters of a theory
 
 The parameters for all of the theories can be found in the `theory.db` file,
-located in the `<NNPDF install location>/share/NNPDF/data` directory. This is
-an sqlite database file.
+located in the `<NNPDF install location>/share/NNPDF/data` directory. This is an
+sqlite database file. The information contained within this file can also be
+viewed [within the docs](theory-indexes).
 
 The tools required to extract the parameters for a given theory are already in
 the validphys framework:

doc/sphinx/source/tutorials/list-resources.md

@@ -1,5 +1,9 @@
 # How to list the available resources
 
+```eval_rst
+.. _vp-list:
+```
+
 ## Using `vp-list`
 
 In order to check what resources are available locally and for download, use