Rename *.text *.md

As luck would have it the only entries where this applied were my own.
The links/references to these files have been changed in the files.

An unfortunate problem is that in 2020/ferguson1 there are several
*.markdown files. I will have to go through these and figure out which
ones should be changed to .md and which ones can be removed. This can
happen later but in the meantime the references are to .md. I believe
the only difference is that the .md has the footer added by the judges.
This was a workaround with the fact that I wasn't sure (and still am not
entirely sure) the generation of the html files will work. It might be
that the .markdown files have the footer and the .md files do not but
this can be dealt with later anyway.

2020/ferguson2/README.md

@@ -42,7 +42,7 @@ A useful man page for this entry.  To render, try:
 
     man ./enigma.1
 
-* recode.markdown ([recode.html][])
+* recode.md ([recode.html][])
 
 Some useful information about recode.c
 
@@ -198,7 +198,7 @@ After that you can input the string and it'll go from there.
 #### <a name="example" href="#toc">An example run</a>
 
 BTW: There's a much more entertaining (and delicious) challenge or exercise in
-[recode.markdown][] (involves [chocolate-cake.html][]). These however show
+[recode.md][] (involves [chocolate-cake.html][]). These however show
 the general program as well as how to use the two winning entries of the Morse
 code that I referred to earlier.
 
@@ -326,7 +326,7 @@ I didn't think of everything. My entry was meant to be a simulator only as far
 as the ciphering goes but I thought this would make it much more interesting:
 make it more flexible by a wrapper program.
 
-For examples using it (and a delicious challenge) see [recode.markdown][]. See
+For examples using it (and a delicious challenge) see [recode.md][]. See
 also [recode.1][] and [enigma.1][] man pages.
 
 
@@ -385,7 +385,7 @@ There are two reflectors and the same applies: in C 0-1 but in human it's
 1-2 (technically these were reflectors B and C in the Enigma machine which I
 display by name in recode.c just like with the rotors).
 
-For more information see [recode.markdown][] or [recode.html][].
+For more information see [recode.md][] or [recode.html][].
 
 BTW: If you need a reminder to go to the gym just do your Enigma ABCs and it
 should help you remember (though not at this time in our world it might help you
@@ -432,16 +432,16 @@ It's an Enigma simulator! Isn't that proof that it's obfuscated itself?! :)
 Silliness aside [obfuscation.txt][] has some of the ways I think this entry is
 obfuscated.  To decipher try:
 
-	    ./recode -Robfuscation.key -fobfuscation.txt | ./prog - 2>/dev/null > obfuscation.markdown
+	    ./recode -Robfuscation.key -fobfuscation.txt | ./prog - 2>/dev/null > obfuscation.md
 
 To encipher:
 
-	    ./recode -Robfuscation.key -fobfuscation.markdown | ./prog - 2>/dev/null > obfuscation.txt
+	    ./recode -Robfuscation.key -fobfuscation.md | ./prog - 2>/dev/null > obfuscation.txt
 
 The file [obfuscation.key][] is the key to decipher/encipher
 [obfuscation.txt][].
 
-For the lazy [obfuscation.markdown][] has the deciphered version. I am afraid
+For the lazy [obfuscation.md][] has the deciphered version. I am afraid
 I'm not so inclined to do that for the cake recipe: the idea there is to make it
 a fun exercise that when solved unlocks a wonderful double-layered chocolate
 fudge cake recipe. But given that my 'Don't tread on me award' entry also
@@ -466,7 +466,7 @@ machines this would not work because they had to choose from a set of rotors and
 there were no duplicates. This shouldn't be a problem here however except that
 it won't be a possible configuration of the real Enigma machine. The `recode`
 program *however does validate this* (except when reading in settings via the
-`-R` option which I explain in the [recode.markdown][] / [recode.html][] file).
+`-R` option which I explain in the [recode.md][] / [recode.html][] file).
 
 *   The way the plugboard - for the machines that had them - is if you connect A
 to B then no other letters can connect to A or B. Earlier there wasn't proper
@@ -667,10 +667,10 @@ that.
 [Interactive Enigma Machine]: http://enigmaco.de/enigma/enigma.html
 [enigma.1]: enigma.1
 [recode.1]: recode.1
-[recode.markdown]: recode.markdown
+[recode.md]: recode.md
 [chocolate-cake.html]: chocolate-cake.html
 [recode.c]: recode.c
-[obfuscation.markdown]: obfuscation.markdown
+[obfuscation.md]: obfuscation.md
 [obfuscation.txt]: obfuscation.txt
 [obfuscation.key]: obfuscation.key
 [Tony Sale's pages on The Enigma cipher machine]: http://www.codesandciphers.co.uk/enigma/index.htm