add links to gerbers in docs

docs/generate_docs.sh

     echo "Generating plots"
     ../pcb/generate_plot.sh
     echo
+    echo "Generating fab"
+    ../pcb/generate_fab.sh
+    echo
 
     echo "Generating plots 2"
     ../pcb2/generate_plot.sh
     echo
+    echo "Generating fab 2"
+    ../pcb2/generate_fab.sh
+    echo
 
     echo "Generating stls"
     ../3dprint/generate_stls.sh
 rm -rf src/plot
 cp -r ../pcb/plot src
 cp -r ../pcb2/plot/* src/plot/
+cp ../pcb/fab.zip src/plot/fab_pcb.zip
+cp ../pcb2/fab.zip src/plot/fab_pcb2.zip
 
 rm -rf src/stl
 cp -r ../3dprint/stl src

docs/src/pcb1.md

 
 [![hand etching prototype pcb](https://www.xythobuz.de/img/lars_13_small.jpg)](https://www.xythobuz.de/img/lars_13.jpg)
 [![assembled prototype](https://www.xythobuz.de/img/lars_10_small.jpg)](https://www.xythobuz.de/img/lars_10.jpg)
+
+You can also [download the Gerber files to order PCBs online](./plot/fab_pcb.zip).

docs/src/pcb1_pcb.md

 
 This page shows the current version of the PCB layout as SVG graphics.
 
+You can [download the Gerber files to order PCBs online](./plot/fab_pcb.zip).
+
 ## 2D PCB Layout
 
 You can also view the [2D PCB layout as PDF](./plot/drumkit.kicad_pcb.pdf).

docs/src/pcb2.md

 # LARS V2
 
 **TODO** this is a work in progress
+
+You can [download the Gerber files to order PCBs online](./plot/fab_pcb2.zip).

docs/src/pcb2_pcb.md

 
 This page shows the current version of the PCB layout as SVG graphics.
 
+You can [download the Gerber files to order PCBs online](./plot/fab_pcb2.zip).
+
 ## 2D PCB Layout
 
 You can also view the [2D PCB layout as PDF](./plot/lars2.kicad_pcb.pdf).