[Doc] Inited description syntax.

doc/SYNTAX.md

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+## Example
+We believe that our explanation will be more efficient if we use some example model.
+We decide to use the same model which we use for testing:
+<img src="https://github.com/vdim/yz/raw/master/doc/son.png" alt="Son model"/>
+
+(This model is developed for the Nest project and its authors are Mikhail Kryshen and Alexander Kolosov.)
+
+Let's consider some snapshot of real data: 
+
+(This figure is produced via the Nest visualization module which is based on indyvon library.)
+
+### Using example
+You can use this example and experiment with further on queries from YZ's repository source code.
+For this you should: 
+1. Execute first seven steps from [testing] (https://github.com/vdim/yz/blob/master/doc/TESTING.md) document.
+
+2. Run REPL:
+<pre><code>vdim:~/yz/test$ lein repl </code></pre>
+
+3. Change namespace (if any):
+	user=> (in-ns 'ru.petrsu.nest.yz.init)
+	#<Namespace ru.petrsu.nest.yz.init>
+
+4. Run query
+	ru.petrsu.nest.yz.init=> (pquery "room" mem)
+
+Note: mem is some instance of the ElementManager.
+
+
+# YZ
+At last let's begin to consider YZ.
+
+## Selection