Fix heading level of 'Try' section

It was agreed to be '## Try:' but there were many files where it was
'### Try:'. This has been corrected.

1989/fubar/README.md

@@ -23,7 +23,7 @@ For more detailed information see [1989 fubar in bugs.md](/bugs.md#1989-fubar).
 ```
 
 
-### Try:
+## Try:
 
 ```sh
 ./try.sh # run on 1 - 7 

1989/jar.2/README.md

@@ -17,7 +17,7 @@ make all
 NOTE: this entry will likely segfault on invalid input.
 
 
-### Try:
+## Try:
 
 ```sh
 ./try.sh

1989/ovdluhe/README.md

@@ -19,7 +19,7 @@ The program stops when it reaches the end of the template buffer
 by chance or is killed.
 
 
-### Try:
+## Try:
 
 ```sh
 ./try.sh ; sleep 2 ; ./try.sh

1989/paul/README.md

@@ -8,7 +8,7 @@ There is an alternate version with a trace routine that the author had commented
 out. See [alternate code](#alternate-code) below for more details.
 
 
-### Try:
+## Try:
 
 ```sh
 ./paul

1989/robison/README.md

@@ -24,7 +24,7 @@ For more detailed information see [1989 robison in bugs.md](/bugs.md#1989-robiso
 ```
 
 
-### Try:
+## Try:
 
 ```sh
 ./robison

1989/roemer/README.md

@@ -5,7 +5,7 @@ make all
 ```
 
 
-### Try:
+## Try:
 
 ```sh
 ./roemer

1989/tromp/README.md

@@ -12,7 +12,7 @@ make all
 ```
 
 
-### Try:
+## Try:
 
 ```sh
 ./tromp 5

1989/vanb/README.md

@@ -5,7 +5,7 @@ make all
 ```
 
 
-### Try:
+## Try:
 
 ```sh
 ./try.sh

1989/westley/README.md

@@ -16,7 +16,7 @@ STATUS: known bug - please help us fix
 For more detailed information see [1989 westley in bugs.md](/bugs.md#1989-westley).
 
 
-### Try:
+## Try:
 
 Try compiling and running the 4 resulting programs like: