Add 2012/tromp/try.sh, update bugs.md + formatting

The try.sh has a variety of commands, some that come from the judges and
some that come from the author.

The bugs.md has features added, not bugs.

The README.md file has been format and typo checked.

The how.md file has been format and typo checked.

The author stated that there is a macro that indicates the term space
but as it's a big number and I don't see it being a problem I did not
(unlike in other cases) add alt code that lets one redefine it.

2012/tromp/how.md

@@ -10,7 +10,7 @@ continuations (see the 3rd reference for details).
 
 The term space holds [lambda
 calculus](https://en.wikipedia.org/wiki/Lambda_calculus) terms in the following
-format. 0 denotes some form of IO; the only four occurrences are at:
+format. 0 denotes some form of I/O; the only four occurrences are at:
 
 ```
   C=13: recognizes end of a byte
@@ -19,10 +19,10 @@ format. 0 denotes some form of IO; the only four occurrences are at:
   C=end: input list, expanded lazily
 ```
 
-`1` denotes a variable, with next entry its de [Bruijn
+`1` denotes a variable, with the next entry its [de Bruijn
 index](https://en.wikipedia.org/wiki/De_Bruijn_index).
 
-`2` denotes application with next entry the size of the term being applied.
+`2` denotes application with the next entry the size of the term being applied.
 
 `3` denotes lambda abstraction.
 
@@ -31,11 +31,11 @@ A closure consists of the following items:
 
 0. pointer to the next closure (as part of an environment), or next record on
 free list.
-1. reference count
-2. pointer to environment
-3. lambda term (index in term space)
+1. reference count.
+2. pointer to environment.
+3. lambda term (index in term space).
 
-Here's what each variable do:
+Here's what each variable does:
 
 ```
 L	Lambda term space