Change alt/orig to build/to use heading levels

As the 'Alternate code' and 'Original code' heading level is now 2 the
'To build' and 'To use' subsections should be level 3, not 4, and also
reworded, this was done:

    sgit -e 's/^#### To build/### Alternate build/g' -e 's/^#### To use/### Alternate use/g' '*README.md'

Many more have to be updated and this will be done manually at another
time.

2012/kang/README.md

@@ -44,13 +44,13 @@ Germans that causes other problems for Germans so if you're German you'll just
 have to deal with it :-) It is, however, good as you can appreciate the entry
 even more.
 
-#### To build:
+### Alternate build:
 
 ```sh
 make alt
 ```
 
-#### To use:
+### Alternate use:
 
 ```sh
 echo vier | ./kang.alt