fix many internal links

Fixed a number of internal links that need to
go to the GitHub site.

Ran `make www` to perform the above.

2020/endoh3/README.md

@@ -25,7 +25,7 @@ code](#alternate-code) below.
 
 ## Alternate code:
 
-An alternate version of this entry, [prog.alt.c](prog.alt.c), is provided.  This
+An alternate version of this entry, [prog.alt.c](%%REPO_URL%%/2020/endoh3/prog.alt.c), is provided.  This
 alternate code uses Unicode letters.
 
 
@@ -55,7 +55,7 @@ You may be tempted to use a mirror. Resist the temptation! Try figuring out how
 the clock hands are drawn.  Can you change the program to make it draw a
 familiar (non-mirrored) clock face? Can you add the second hand?
 
-When using the [run_clock.sh](run_clock.sh) shell script, your perception of
+When using the [run_clock.sh](%%REPO_URL%%/2020/endoh3/run_clock.sh) shell script, your perception of
 time might depend on what time it is.
 
 

2020/endoh3/index.html

@@ -387,7 +387,7 @@ code</a> below.</p>
 <pre><code>    ./run_clock
     # And watch closely for 15-20 seconds</code></pre>
 <h2 id="alternate-code">Alternate code:</h2>
-<p>An alternate version of this entry, <a href="prog.alt.c">prog.alt.c</a>, is provided. This
+<p>An alternate version of this entry, <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2020/endoh3/prog.alt.c">prog.alt.c</a>, is provided. This
 alternate code uses Unicode letters.</p>
 <h3 id="alternate-build">Alternate build:</h3>
 <pre><code>    make alt</code></pre>
@@ -400,7 +400,7 @@ alternate code uses Unicode letters.</p>
 <p>You may be tempted to use a mirror. Resist the temptation! Try figuring out how
 the clock hands are drawn. Can you change the program to make it draw a
 familiar (non-mirrored) clock face? Can you add the second hand?</p>
-<p>When using the <a href="run_clock.sh">run_clock.sh</a> shell script, your perception of
+<p>When using the <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2020/endoh3/run_clock.sh">run_clock.sh</a> shell script, your perception of
 time might depend on what time it is.</p>
 <h2 id="authors-remarks">Author’s remarks:</h2>
 <p>Prepare a mirror!</p>