Avoid confusing MAY clause

[stain]

Avoids

The base directory MAY have any name

... as it implies you should only use "any name" if you really know what you are doing. But really we don't recommend any particular name, so we can't use MAY here.

From RFC2119:

5. MAY This word, or the adjective "OPTIONAL", mean that an item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because the vendor feels that it enhances the product while another vendor may omit the same item. An implementation which does not include a particular option MUST be prepared to interoperate with another implementation which does include the option, though perhaps with reduced functionality. In the same vein an implementation which does include a particular option MUST be prepared to interoperate with another implementation which does not include the option (except, of course, for the feature the option provides.)

[justinlittman]

Concur.