Add book link to the documentation

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

docs/utils.py

@@ -1,5 +1,11 @@
 from __future__ import unicode_literals
 
+import shutil
+from pathlib2 import Path
+import sphinx_rtd_theme
+
+from mayan.apps.storage.utils import patch_files
+
 
 def load_env_file(filename='../config.env'):
     result = {}
@@ -19,3 +25,30 @@ def generate_substitutions(dictionary):
         result.append(('|{}|'.format(key), value))
 
     return result
+
+
+def patch_theme_template(app, templates_path):
+    package_path = Path(sphinx_rtd_theme.__file__)
+    source_file_path = package_path.parent / 'layout.html'
+    destination_path = Path(app.srcdir) / templates_path
+    destination_file_path = destination_path / 'layout.html'
+
+    with source_file_path.open(mode='r') as source_file_object:
+        with destination_file_path.open(mode='w+') as destination_file_object:
+            shutil.copyfileobj(
+                fsrc=source_file_object, fdst=destination_file_object
+            )
+
+    patch_files(
+        path=destination_path, replace_list=[
+            {
+                'filename_pattern': 'layout.html',
+                'content_patterns': [
+                    {
+                        'search': '</div>\n    </nav>\n\n    <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap">',
+                        'replace': '{% include "message_area.html" %}</div>\n    </nav>\n\n    <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap">',
+                    },
+                ]
+            }
+        ]
+    )