[sphinx] Putting back annotator

doc/annotators.rst

+.. _bob.bio.base.annotators:
+
+==============================
+Annotating biometric databases
+==============================
+
+It is often required to annotate the biometric samples before running
+experiments. This often happens in face biometrics where each face is detected
+and location of landmarks on the face is saved prior to running experiments.
+
+To facilitate the process of annotating a new database, this package provides
+a command-line script:
+
+.. code-block:: sh
+
+    $ bob bio annotate --help
+
+This script accepts two main parameters a database object that inherits from
+:any:`bob.bio.base.database.BioDatabase` and an annotator object that inherits
+from :any:`bob.bio.base.annotator.Annotator`. Please see the help message of
+the script for more information.
+
+The script can also be run in parallel using :ref:`gridtk`:
+
+.. code-block:: sh
+
+    $ jman submit --array 64 -- bob bio annotate /path/to/config.py --array 64
+
+The number that is given to the ``--array`` options should match.
+
+You can find the list of readily available annotator configurations using the
+``resources.py`` command:
+
+.. code-block:: sh
+
+    $ resources.py --types annotator

doc/index.rst

@@ -84,6 +84,7 @@ Users Guide
    vanilla_biometrics_intro
    vanilla_biometrics_features
    vanilla_biometrics_score_normalization
+   annotators
    legacy