Significant cleanup/rewrite of GEOM Striping section.

• This chapter claims to be about striping, but talks about disk concatenation in some paragraphs. Remove all references to concatenation, add a brief paragraph explaining what striping is and why it provides superior I/O performance through parallel I/O to multiple disks simultaneously.

• Do not alternate between calling striping raid0 and raid1. Consistently refer to it as raid0, as raid1 is mirroring.

• Cleanup / reorganize the example set of commands for creating a stripe of two ATA disks. Wrap it in a DocBook <procedure> tag with individual <steps> to provide a title for this procedure and make the numbered steps very clear to follow without confusing verbiage and side tangents adding confusion.

• Expand 'redundant array of inexpensive disks' in <acronym> tag for mouseover on first use of HTML output.

• Remove some poorly worded, confusing, and contradictory sentences and paragraphs.