Updates to 2020/ferguson2

Added testing procedure (markdown, html: testing-procedure.{md,html}).
Updated the recode.{md,html} and README.md for this as well.

Updated the hidden message file (enigma.html) for a bit more fun.

Updated manifest, rebuilt index.html and .entry.json.

2020/ferguson2/README.md

@@ -1,4 +1,4 @@
-%%REPO_URL%%/## To build:
+## To build:
 
 ``` <!---sh-->
     make
@@ -122,8 +122,12 @@ There is a good deal of useful documentation that is provided with this entry:
 * [enigma.html][]
     - NOTE: see [recode.html][] (or [recode.html](recode.html) for details about how to decrypt this!
 
+* [testing-procedure][]
+	- How the author tested the code and why it was necessary to do it in the way it was
 
 [recode.html]: recode.html
+[enigma.html]: enigma.html
+[testing-procedure]: testing-procedure.html
 
 
 ## Author's remarks:
@@ -840,6 +844,13 @@ don't think there need be any addition to the recode program - at least not
 that.
 
 
+### Testing procedure
+
+There was a need for a testing procedure as a single character difference will
+change the rest of the text. If you wish to see how I went about this see
+[testing-procedure.html](testing-procedure.html).
+
+
 [1992 Worst Abuse of the Rules]: ../../1992/nathan/index.html
 [1998 ASCII / Morse code translator]: ../../1998/dorssel/index.html
 [2014 Morse audio transcoder]: ../../2014/vik/index.html