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.

1984/anonymous/README.md

@@ -21,13 +21,13 @@ in order to show the code that was turned into the
 [tattoo](https://web.archive.org/web/20070120220721/https://thomasscovell.com/tattoo.php),
 as the alternate code. See below in the tattoo side-by-side with the code.
 
-#### To build:
+### Alternate build:
 
 ```sh
 make alt
 ```
 
-#### To use:
+### Alternate use:
 
 NOTE: this version might not work on some systems like macOS.