Missing targets or Doc error

[David Ronis]

The documentation says that there are build targets like:

`bubblestrap'
     Once bootstrapped, this incrementally rebuilds each of the three
     stages, one at a time.  It does this by "bubbling" the stages up
     from their subdirectories, rebuilding them, and copying them back
     to their subdirectories.  This will allow you to, for example,
     quickly rebuild a bootstrapped compiler after changing the
     sources, without having to do a full bootstrap.

`quickstrap'
     Rebuilds the most recently built stage.  Since each stage requires
     special invocation, using this target means you don't have to keep
     track of which stage you're on or what invocation that stage needs.

`cleanstrap'
     Removed everything (`make clean') and rebuilds (`make bootstrap').


They are no longer supported in the Makefile.  If this is not an
error, the documentation should be fixed.

David