doc: Misc improvements

  * Admonition to be sure to clean up state in setup()
  * More thorough vetting of new versions in production in server admin page
  * Typos

  Resolves #319.

doc/making-a-visualizer.md

@@ -204,11 +204,11 @@ checkParameters(), but at least the person running the visualization will be
 notified.
 
 Finally, note that checkParameters is called with _tentative_ parameter values
-and is not guaranteed that those parameter values will actually be loaded into
-the visualizer. So (a) only access the values through the passed-in `params`
-object, not thhrough the visualizer itself, and (b) don't start setting up for
-visualization using those values: leave that to one of the set-up functions
-discussed below.
+and there is no guarantee that those parameter values will actually be loaded
+into the visualizer. So (a) only access the values through the passed-in
+`params` object, not through the visualizer itself, and (b) don't start
+setting up for visualization using those values: leave that to one of the
+set-up functions discussed [below](#set-up-the-visualizer-often-used).
 
 -   **p5 Template:** Make sure that the step size is positive.
 
@@ -282,7 +282,14 @@ that new canvas is a different size than the previous one. However, the
 visualizer object constructor is not re-run and any data stored in variables
 in the visualizer object persists. Those defaults mean that you have the
 option to forgo re-doing expensive pre-computations: if they don't need sketch
-access, you can put such calculations in `presketch()`.
+access, you can put such calculations in `presketch()`. But the flip side is
+that you can't rely on property initializers, your class constructor, or on
+(say) checkParameters() to put your other visualizer instance properties in a
+"clean" state. For example, if you need some array to be all zeros when you
+start drawing your visualization, and previous calls to `draw()` may have
+changed some of those array entries, you need to zero it out in `setup()`
+because after a parameter change, that's the only preparation function that
+will by default be called before going back into the drawing loop.
 
 For even greater customization of what happens when, you can override/extend
 `reset()` from the `P5Visualizer` base class, or you can define a `resized()`

doc/server-administration.md

@@ -21,9 +21,34 @@ subdirectory of the frontscope clone go live instantly.
 
 ## How to deploy a new version of frontscope
 
+We presume that we are only going to install the current version of the `main`
+branch from the standard repository onto the production machine. This version
+has the advantages of having undergone code review and automated unit and
+end-to-end tests. Nevertheless, before installing any version, you should
+manually make sure it seems to be working properly, one last time:
+
+1. Make sure you have the latest version of `main` from the standard
+   repository pulled and checked out on your own machine (or in any case, a
+   non-production computer).
+2. Execute `npm run test:e2e`.
+3. Assuming all passes, execute `npm run preview`.
+4. Connect to the provided URL, and try a few things with the resulting
+   Numberscope instance that you've never tried before, and a couple that you
+   have done many times, to make sure that all seems to be operating.
+
+When you've done all that, it's OK to install that version on the official
+numberscope server.
+
 1. Log into the numberscope server and `cd ~scope/repos/frontscope`.
 2. Execute `sudo -u scope git pull`.
 3. Execute `sudo -u scope npm install`.
 4. Execute `sudo -u scope npm run build`.
-5. Check that the numberscope front end at the primary server URL is working
-   and serving the updated version of Numberscope.
+5. Execute `sudo systemctl restart numberscope`. Note that this step is may
+   generally be unnecessary for the service to update to the new version, but
+   is good hygeine for the server in any case.
+6. Execture `sudo systemctl status numberscope` to verify that the server
+   believes the service is running.
+7. Check that the numberscope front end at the primary server URL is working
+   and serving the updated version of Numberscope (by browsing to that URL and
+   again trying some tasks, especially ones that exercise any new features in
+   the version you have just installed).