fix even more broken markdown links

Added `bin/find-missing-links.sh` tool to check for
markdown links to missing local files.

Regarding the missing link tool:

```
    Here be extended regular expression magic dragons! :-)
```

Added `make find_missing_links` to the top level Makefile.

Added `make find_missing_links` to `make www` and `make quick_www`.

Ran `make www` to perform the above.

TODO: Fix markdown links to missing local files.

1992/buzzard.2/README.md

@@ -157,7 +157,7 @@ tackle this project.
 on smaller machines; `m[]` needs to be at least 2000 long, though.
 
 I say `first` is portable mainly because it uses native types.  Unlike
-[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language), which
+[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)), which
 traditionally allows byte and multi-byte operations, all operations are
 performed on C `int`s.  That means `first` code is only as portable as the same
 code would be in C.  As in C, the result of dividing `-1` by `2` is machine (or
@@ -205,7 +205,7 @@ represents a step backwards, in more ways than one.)
 ### What exactly is `first`, then?
 
 `first` is a tiny interpreter which implements a sufficient pseudo-subset of
-[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)) to allow it
+[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)) to allow it
 to bootstrap a relatively complete version of FORTH (based loosely on forth79),
 which I call THIRD.  Complete relative to what, I'm not sure.
 
@@ -217,11 +217,11 @@ the design file, design, I give a justification for why each primitive in
 
 THIRD is sorta slow, because `first` has so few primitives that many things that
 are primitives in
-[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)) (like swap)
+[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)) (like swap)
 take a significant amount of time in THIRD.
 
 When you get the `Ok.` message from `third`, try out some sample
-[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)) code
+[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)) code
 (`first` has no way of knowing if keyboard input is waiting, so it can't actually prompt
 you in a normal way.  It only prints `'Ok.'` after you define a word).
 
@@ -266,7 +266,7 @@ If you compile the basic THIRD system without the help word (strings take up one
 1000 `int`s (plus the return stack).
 
 Thus THIRD gives you a relatively complete
-[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)) system in
+[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language)) system in
 less than 700 chars of C source + about 1000 `int`s of memory--and it's portable
 too (you could copy over the THIRD memory dump to another machine, in theory).
 If the above numbers seem to you to be mixing apples and oranges (C source and

1992/buzzard.2/index.html

@@ -484,7 +484,7 @@ tackle this project.</p>
 <p><code>first</code> is reasonably portable. You may need to adjust the size of the buffers
 on smaller machines; <code>m[]</code> needs to be at least 2000 long, though.</p>
 <p>I say <code>first</code> is portable mainly because it uses native types. Unlike
-[FORTH](https://en.wikipedia.org/wiki/Forth_(programming_language), which
+<a href="https://en.wikipedia.org/wiki/Forth_(programming_language)">FORTH</a>, which
 traditionally allows byte and multi-byte operations, all operations are
 performed on C <code>int</code>s. That means <code>first</code> code is only as portable as the same
 code would be in C. As in C, the result of dividing <code>-1</code> by <code>2</code> is machine (or