Fixes in 1998 html files

This includes some notices to those who wish for a greater challenge.

In the 1998/schweikh3 the man page (and its copy to demonstrate the
entry) have been updated slightly but only in comment (move 'or' from
the command suggested to render it in text to its own line before the
next command also in comment).

The bugs file was updated for an entry or two.

1998/banks/index.html

@@ -437,8 +437,8 @@ the throttle up and down to <code>u</code> and <code>d</code>:</p>
 <pre><code>    make clobber IT=XK_u DT=XK_d all</code></pre>
 <p>because in the header file you can see that <code>XK_u</code> corresponds to <code>u</code> and <code>XK_d</code>
 corresponds to <code>d</code>:</p>
-<pre><code>    #define XK_d                             0x0064  /* U+0064 LATIN SMALL LETTER D */
-    #define XK_u                             0x0075  /* U+0075 LATIN SMALL LETTER U */</code></pre>
+<pre><code>    #define XK_d 0x0064  /* U+0064 LATIN SMALL LETTER D */
+    #define XK_u 0x0075  /* U+0075 LATIN SMALL LETTER U */</code></pre>
 <p>Note that the <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1998/banks/keysym.h">keysym.h</a> file is not complete from X11; it’s just the
 more likely candidates (and some that are probably unlikely :-) ).</p>
 <p>The upper case letters would be <code>XK_U</code> and <code>XK_D</code> and you can search the header