Refs #9584 Add example for Symmetrise.

Code/Mantid/docs/source/algorithms/Symmetrise-v1.rst

@@ -14,4 +14,26 @@ moduli of xmin & xmax are different. Typically xmax is > mod(xmin). A
 negative value of x is chosen (Xcut) so that the curve for mod(Xcut) to
 xmax is reflected and inserted for x less than the Xcut.
 
+Usage
+-----
+
+**Example - Running Symmetrise on an asymmetric workspace.**
+
+.. testcode:: ExSymmetriseSimple
+
+    import numpy as np
+
+    #create an asymmetric line shape
+    def rayleigh(x, sigma):
+      return (x / sigma**2) * np.exp( -x**2 / (2*sigma**2))
+
+    dataX = np.arange(0, 10, 0.01)
+    dataY = rayleigh(dataX, 1)
+
+    ws = CreateWorkspace(dataX, dataY)
+    ws = ScaleX(ws, -1, "Add") #centre the peak over 0
+
+    ws = RenameWorkspace(ws, OutputWorkspace="iris00001_graphite002_red")
+    Symmetrise('00001', '-0.001', InputType='Workspace')
+
 .. categories::