Changing heading level of 'Alternate code'

Change level 3 (###) to level 2 (##):

    sgit -e 's/^### \(Alternate code\)/## \1/g' '*README.md'

which is the same as:

    sgit -e 's/^### Alternate code/## Alternate code/g' '*README.md'

This is per discussion in GitHub.

1987/hines/README.md

@@ -21,7 +21,7 @@ make all
 ./hines hines.c
 ```
 
-### Alternate code:
+## Alternate code:
 
 An alternate version of this entry is in [hines.alt.c](hines.alt.c). With older
 compilers you can try the alt version:

1987/westley/README.md

@@ -16,7 +16,7 @@ make all
 ./westley
 ```
 
-### Alternate code:
+## Alternate code:
 
 If you have an older compiler you can try compiling the original source code
 which is true symmetry: