Typo fix in 2020/ferguson2/README.md

Extraneous ')' added by accident when adding a link yesterday.

I also, unrelated, clarified in a spot or two that one should use the
markdown files if reading on GitHub. This however is not consistent and
needs to be done throughout all files probably including other entries
(mostly README.md but there are certainly others).

2020/ferguson2/README.md

@@ -119,7 +119,7 @@ There is a good deal of useful documentation that is provided with this entry:
 ## Author's remarks:
 
 My remarks about my [Heer
-'Army'](https://en.wikipedia.org/wiki/German_Army_(1935%E2%80%931945)) and
+'Army'](https://en.wikipedia.org/wiki/German_Army_(1935%E2%80%931945) and
 [Luftwaffe 'Air Force'](https://en.wikipedia.org/wiki/Luftwaffe) [Enigma
 machine](https://en.wikipedia.org/wiki/Enigma_machine) simulator for
 the 27th IOCCC.
@@ -271,7 +271,7 @@ After that you can input the string and it'll go from there.
 #### <a name="example" href="#toc">Example run</a>
 
 BTW: There's a much more entertaining (and delicious) challenge or exercise in
-[recode.html][] (markdown version [recode.md](recode.md)) (involves
+[recode.html][] (markdown version [recode.md](recode.md) if reading on GitHub) (involves
 [chocolate-cake.html][]) though one might need a different kind of exercise
 after taking up the challenge! :-) These however show the general program as
 well as how to use the two winning entries of the Morse code that I referred to
@@ -419,8 +419,8 @@ 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.html][]/[recode.md](recode.md). See also the [recode.1][] and
+For examples using it (and a delicious challenge) see [recode.html][] (or
+[recode.md](recode.md) if reading on GitHub). See also the [recode.1][] and
 [enigma.1][] man pages.