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.

2020/endoh2/spoiler/spoiler.html

@@ -139,14 +139,14 @@
 <p>The source code of the font is <a href="glyphs.txt">glyphs.txt</a>, which is a sequence of
 chunks that is a ASCII code (65-90) followed by points data: <code>x,y,ctrl</code>.</p>
 <p>If <code>ctrl</code> is 1, the point is used as control point for quadratic bezier curve.</p>
-<p><a href="code.c">code.c</a> is the main logic for the program, which has some placeholders
+<p><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2020/endoh2/code.c">code.c</a> is the main logic for the program, which has some placeholders
 for font data and something.</p>
 <p>It decompresses the font data and renders a given text by projection. It
 exploits <code>C99</code>’s <code>double complex</code> type to represent 2D points, but carefully
 coded so that it does not require any <code>math.h</code> functions; you don’t have to pass
 <code>-lm</code> to <code>cc</code>.</p>
-<p><a href="tmpl.txt">tmpl.txt</a> is a template for the program. <a href="gen.rb">gen.rb</a> composes
-the all items and generates <a href="prog.c">prog.c</a>.</p>
+<p><a href="tmpl.txt">tmpl.txt</a> is a template for the program. <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2020/endoh2/gen.rb">gen.rb</a> composes
+the all items and generates <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2020/endoh2/prog.c">prog.c</a>.</p>
 <hr style="width:10%;text-align:left;margin-left:0">
 <p>Jump to: <a href="#">top</a></p>
 <!--

2020/endoh2/spoiler/spoiler.md

@@ -7,7 +7,7 @@ chunks that is a ASCII code (65-90) followed by points data: `x,y,ctrl`.
 
 If `ctrl` is 1, the point is used as control point for quadratic bezier curve.
 
-[code.c](code.c) is the main logic for the program, which has some placeholders
+[code.c](%%REPO_URL%%/2020/endoh2/code.c) is the main logic for the program, which has some placeholders
 for font data and something.
 
 It decompresses the font data and renders a given text by projection.  It
@@ -15,8 +15,8 @@ exploits `C99`'s `double complex` type to represent 2D points, but carefully
 coded so that it does not require any `math.h` functions; you don't have to pass
 `-lm` to `cc`.
 
-[tmpl.txt](tmpl.txt) is a template for the program.  [gen.rb](gen.rb) composes
-the all items and generates [prog.c](prog.c).
+[tmpl.txt](tmpl.txt) is a template for the program.  [gen.rb](%%REPO_URL%%/2020/endoh2/gen.rb) composes
+the all items and generates [prog.c](%%REPO_URL%%/2020/endoh2/prog.c).
 
 
 <hr style="width:10%;text-align:left;margin-left:0">