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.

1989/ovdluhe/README.md

@@ -35,7 +35,7 @@ by chance or is killed.
 ./ovdluhe < README.md
 ```
 
-### Alternate code:
+## Alternate code:
 
 The author suggested that one varies the definition of `P` from 2 through 10. As
 it's a `#define` it's easy to set up. To use try: