adjustments to new graph traversal for developers

suggested by @joshmoore, @hflynn, @pwalczysko, @bpindelski
re-wrap paragraph
add overview box

suggested by @hflynn
Initial FAQ reference removal
Adding performance stuff to troubelshooting
Adding ldap FAQ info
merge develop -Dorg -Ssuccess-only: PR 1038 (updating web doc for embedding viewer)
merge develop -Dorg -Ssuccess-only: PR 1041 (Units documentation)
merge develop -Dorg -Ssuccess-only: PR 1042 (document graph traversal reimplementation for developers)
merge develop -Dorg -Ssuccess-only: PR 1044 (Faq stuff)
merge develop -Dorg -Ssuccess-only

Repository: openmicroscopy/ome-documentation
Already up-to-date.

Merged PRs:
  # PR 1038 aleksandra-tarkowska 'updating web doc for embedding viewer'
  # PR 1041 joshmoore 'Units documentation'
  # PR 1042 mtbc 'document graph traversal reimplementation for developers'
  # PR 1044 hflynn 'Faq stuff'

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