Missing Install Procedure for Documentation Tree

[Stirling Westrup <swestrup@…>]

Currently Boost builds the documentation tree, but does not install it. There is no method provided for installing the documentation tree, and no way, without manually checking, to ensure that all internal documentation links are relative and will survive relocating the documentation to a standard documentation repository.

Some packaged distributions, such as Debian, DO provide install methods for the documentation. One such method should be chosen and backported to the main Boost repository.