Added documentatio for the new output

CHANGELOG.md

@@ -6,6 +6,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 
 ## [Unreleased]
+### Added
+- STEP 3D model generation
 
 ## [0.3.0] - 2020-06-14
 ### Added

README.md

@@ -12,6 +12,7 @@ For example, it's common that you might want for each board rev:
 * Gerbers, drills and drill maps for a fab in their favourite format
 * Fab docs for the assembler
 * Pick and place files
+* PCB 3D model in STEP format
 
 You want to do this in a one-touch way, and make sure everything you need to
 do so it securely saved in version control, not on the back of an old
@@ -144,6 +145,8 @@ The available values for *type* are:
 - Bill of Materials
     - `kibom` BoM in HTML or CSV format generated by [KiBoM](https://github.com/INTI-CMNB/KiBoM)
     - `ibom` Interactive HTML BoM generated by [InteractiveHtmlBom](https://github.com/INTI-CMNB/InteractiveHtmlBom)
+- 3D model:
+    - `step` *Standard for the Exchange of Product Data* for the PCB
 
 Here is an example of a configuration file to generate the gerbers for the top and bottom layers:
 
@@ -288,6 +291,13 @@ The valid formats are `hpgl`, `ps`, `gerber`, `dxf`, `svg` and `pdf`. Example:
 
 - `output` filename for the output PDF
 
+### STEP options
+
+- `metric_units` (boolean) use metric units instead of inches.
+- `origin` (string) determines the coordinates origin. Using `grid` the coordinates are the same as you have in the design sheet. The `drill` option uses the auxiliar reference defined by the user. You can define any other origin using the format "X,Y", i.e. "3.2,-10".
+- `no_virtual` (boolean optional=false) used to exclude 3D models for components with *virtual* attribute.
+- `min_distance` (numeric default=0.01 mm) the minimum distance between points to treat them as separate ones.
+- `output` (string optional=project.step) name for the generated STEP file.
 
 ## Using KiPlot