Initial version of unit testing documentation

This commit includes the 'User guide' and 'Implementing tests' sections
for helping people building, running and writing unit tests. A more
detailed version of documentation is available under the 'Component
user manuals section'.

Change-Id: I67e93ac805d1f4e7727964f3d95a70436ae34733
Signed-off-by: Imre Kis <imre.kis@arm.com>
diff --git a/docs/license.rst b/docs/license.rst
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+License
+=======
+
+The software is provided under a BSD-3-Clause license (below). Contributions to
+this project are accepted under the same license with developer sign-off as
+described in the :ref:`Contributor's guide`.
+
+::
+
+  Copyright (c) [XXXX-]YYYY, <OWNER>. All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without modification,
+  are permitted provided that the following conditions are met:
+
+  -  Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+  -  Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+  -  Neither the name of Arm nor the names of its contributors may be used to
+  endorse or promote products derived from this software without specific
+  prior written permission.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+  ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+  ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+SPDX Identifiers
+----------------
+
+Individual files contain the following tag instead of the full license text.
+
+::
+
+    SPDX-License-Identifier:    BSD-3-Clause
+
+This enables machine processing of license information based on the SPDX
+License Identifiers that are here available: http://spdx.org/licenses/
+