add some tool descriptions

Blendercam-Tools.md

@@ -3,13 +3,13 @@ Blendercam has a number of curve operators that will modify curves to make them
 * [View Tool Shelf](#view-tool-shelf)
 * [View Blendercam Tools](#view-blendercam-tools)
 * [Curve Boolean](#curve-boolean)
-* [Intarsian](#intarsian)
+* [Intarsion](#intarsion)
 * [Add Overcuts](#add-overcuts)
 * [Silhouette Offset](#silhouette-offset)
 * [C-Remove Doubles](#c-remove-doubles)
 
 ## View Tool Shelf
-If the Tool Shelf is not visible on the left of the 3D view then use the short cut **T** or use the mouse left button select the small + near the top left border of the 3D view.
+If the Tool Shelf is not visible on the left of the 3D view then use the short cut **T** or use the mouse to left button select the small **+** near the top left border of the 3D view.
 
 ![Tool Shelf view](https://cloud.githubusercontent.com/assets/648108/12375196/8568d218-bc8d-11e5-8729-56c322bc7065.png) 
 
@@ -20,11 +20,19 @@ If the Tool Shelf is not visible on the left of the 3D view then use the short c
 * **2** - Select the expansion arrow to see the tool buttons available.
 
 ## Curve Boolean
+Perform a Boolean operation on two curves.  The Boolean operations that can be performed are:
+  * Union
+  * Difference
+  * Intersect
 
-## Intarsian
+## Intarsion
+Makes a curve cuttable from both the inside and outside.  This is useful for [intarsia](https://en.wikipedia.org/wiki/Intarsia), inlays, and joints.  All sharp edges are rounded over using the cutter diameter. Only works on curves.
 
 ## Add Overcuts
+Adds overcuts for slots.
 
 ## Silhouette Offset
+This operator finds the silhouette of objects(meshes, curves just get converted) and offsets it.
 
-## C-Remove Doubles
+## C-Remove Doubles
+Curve remove doubles - warning, removes beziers!