samples: doc: clean-up table of contents for board samples

Board samples were listed in a very flat way before.
This commit introduces the appropriate toctrees to fix this.

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

samples/boards/96boards/argonkey/index.rst

@@ -0,0 +1,10 @@
+.. _argonkey-samples:
+
+Argonkey Samples
+################
+
+.. toctree::
+   :maxdepth: 1
+   :glob:
+
+   */*

samples/boards/96boards/index.rst

@@ -0,0 +1,10 @@
+.. _96boards_samples:
+
+96Boards
+========
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   */*

samples/boards/bbc/index.rst

@@ -0,0 +1,11 @@
+.. _bbc_samples:
+
+BBC
+===
+
+.. toctree::
+   :titlesonly:
+   :maxdepth: 1
+   :glob:
+
+   */*

samples/boards/boards.rst

@@ -4,7 +4,8 @@ Board-specific samples
 ######################
 
 .. toctree::
-   :maxdepth: 1
+   :titlesonly:
+   :maxdepth: 2
    :glob:
 
-   **/*
+   */*

samples/boards/enjoydigital/index.rst

@@ -0,0 +1,10 @@
+.. _enjoydigital_samples:
+
+EnjoyDigital
+============
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/espressif/index.rst

@@ -0,0 +1,10 @@
+.. _espressif_samples:
+
+Espressif
+=========
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/google/index.rst

@@ -0,0 +1,10 @@
+.. _google_samples:
+
+Google
+======
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/intel/index.rst

@@ -0,0 +1,10 @@
+.. _intel_samples:
+
+Intel
+=====
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/microchip/index.rst

@@ -0,0 +1,10 @@
+.. _microchip_samples:
+
+Microchip
+=========
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/nordic/index.rst

@@ -0,0 +1,10 @@
+.. _nordic_samples:
+
+Nordic Semiconductor
+====================
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/nxp/index.rst

@@ -0,0 +1,10 @@
+.. _nxp_samples:
+
+NXP
+===
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/phytec/index.rst

@@ -0,0 +1,10 @@
+.. _phytec_samples:
+
+PHYTEC
+======
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/quicklogic/index.rst

@@ -0,0 +1,10 @@
+.. _quicklogic_samples:
+
+QuickLogic Corp.
+================
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/st/index.rst

@@ -0,0 +1,10 @@
+.. _st_samples:
+
+STMicroelectronics
+==================
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*

samples/boards/ti/index.rst

@@ -0,0 +1,10 @@
+.. _ti_samples:
+
+Texas Instruments
+=================
+
+.. toctree::
+   :titlesonly:
+   :glob:
+
+   **/*