Bug 1547812 - Add dom/docs for design documents about the DOM. r=nika

Differential Revision: https://phabricator.services.mozilla.com/D29251

--HG--
extra : moz-landing-system : lando

dom/docs/Fission.rst

@@ -0,0 +1,13 @@
+Fission
+=======
+
+Fission is a cross-functional project for revamping and strengthening the architecture of the Firefox browser.
+
+The work is tracked under this bug (https://bugzilla.mozilla.org/show_bug.cgi?id=fission). See this Wiki page for more details (https://wiki.mozilla.org/Project_Fission).
+
+We don't have an all-encompassing design document at this time. This may change in the future.
+
+IPC Diagram
+-----------
+
+.. image:: Fission-IPC-Diagram.svg

dom/docs/index.rst

@@ -0,0 +1,9 @@
+DOM
+===
+
+These linked pages contain design documents for the DOM implementation in Gecko. They live in-tree under the 'dom/docs' directory.
+
+.. toctree::
+   :maxdepth: 1
+
+   Fission

dom/moz.build

@@ -121,3 +121,4 @@ TEST_DIRS += [
 if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('gtk3', 'cocoa', 'windows'):
     TEST_DIRS += ['plugins/test']
 
+SPHINX_TREES['dom'] = 'docs'