fix links in entry HTML files other than index.html

Fixed internal links in entry HTML files other than index.html.

Removed links to markdown files that otherwise used to
generate HTML files other than index.html.

Ran `make gen_other_html` to perform the above.

1994/shapiro/shapiro.html

@@ -135,7 +135,7 @@
 
 <!-- BEFORE: 1st line of markdown file: 1994/shapiro/shapiro.md -->
 <h1 id="hints">HINTS</h1>
-<p>For the first program (<a href="shapiro.c">shapiro.c</a>):</p>
+<p>For the first program (<a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/1994/shapiro/shapiro.c">shapiro.c</a>):</p>
 <p>This is a very simple program:</p>
 <pre><code>     1. #include &lt;stdio.h&gt;
      2. main()

1994/shapiro/shapiro.md

@@ -1,6 +1,6 @@
 # HINTS
 
-For the first program ([shapiro.c](shapiro.c)):
+For the first program ([shapiro.c](%%REPO_URL%%/1994/shapiro/shapiro.c)):
 
 
 This is a very simple program: