sphinx: insert blank below between title and toc

Whenever a TOC follows a title/heading, a blank line is missing. So
let's add it explicitely.

(From yocto-docs rev: 600b6fe7837dd817d32350e1a45431bdcfe8ebbd)

Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/adt-manual/adt-manual.rst

@@ -4,6 +4,8 @@
 Yocto Project Application Developer's Guide
 ===========================================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/bsp-guide/bsp-guide.rst

@@ -4,6 +4,8 @@
 Yocto Project Board Support Package Developer's Guide
 =====================================================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/dev-manual/dev-manual.rst

@@ -4,6 +4,8 @@
 Yocto Project Development Tasks Manual
 ======================================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/index.rst

@@ -8,6 +8,8 @@
 Welcome to The Yocto Project's documentation!
 =============================================
 
+|
+
 .. toctree::
    :maxdepth: 1
    :caption: Introduction and Overview

documentation/kernel-dev/kernel-dev.rst

@@ -4,6 +4,8 @@
 Yocto Project Linux Kernel Development Manual
 =============================================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/overview-manual/overview-manual.rst

@@ -4,6 +4,8 @@
 Yocto Project Overview and Concepts Manual
 ==========================================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/profile-manual/profile-manual.rst

@@ -4,6 +4,8 @@
 Yocto Project Profiling and Tracing Manual
 ==========================================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/ref-manual/ref-manual.rst

@@ -4,6 +4,8 @@
 Yocto Project Reference Manual
 ==============================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/sdk-manual/sdk-manual.rst

@@ -4,6 +4,8 @@
 Yocto Project Application Development and the Extensible Software Development Kit (eSDK)
 ========================================================================================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/test-manual/test-manual.rst

@@ -4,6 +4,8 @@
 Yocto Project Test Environment Manual
 =====================================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered:

documentation/toaster-manual/toaster-manual.rst

@@ -4,6 +4,8 @@
 Toaster User Manual
 ===================
 
+|
+
 .. toctree::
    :caption: Table of Contents
    :numbered: