Add note about stroke-width to README

Per issue #1

README.md

@@ -35,7 +35,7 @@ $ node sketch001.js
 [output written to out.svg, which you can open directly in a browser]
 ```
 
-There are a number of demo "sketches", found in `sketches/sketchNNN.js`. The format should be relatively obvious, but a sketch is implemented as a call to `makeSketch` that provides a callback function to fill/define the voxels of the scene. The `padFrac` argument is the (fractional) padding around the edges of the render. The `ops` argument to the callback is an object with a handful of useful voxel operations (defined in `core/scene.js`, `const ops = {...`). Note that many of the ops have a random element; re-run the sketch to get a new variation.
+There are a number of demo "sketches", found in `sketches/sketchNNN.js`. The format should be relatively obvious, but a sketch is implemented as a call to `makeSketch` that provides a callback function to fill/define the voxels of the scene. The `padFrac` argument is the (fractional) padding around the edges of the render. The `ops` argument to the callback is an object with a handful of useful voxel operations (defined in `core/scene.js`, `const ops = {...`). Note that many of the ops have a random element; re-run the sketch to get a new variation. The width of the lines in the SVG is currently hard-coded, but it's easy to modify by hand. It appears in one place at the top of the SVG file (the `stroke-width` attribute of the `<g>` element), and is defined in `core/render.js`.
 
 To understand the available ops, it's useful to look at the demo sketches, but here is some brief documentation. Voxel coordinates arguments are given as plain old JS objects, like `{x: 1, y: 2, z: 3}`, with axes defined per the Math/Tech Notes section above. The `fill` argument of ops is to be 0 or 1, corresponding to empty or solid.