Move puppet config subcommand to 'occasionally useful' section

Now that it can properly handle config blocks and can set values for
settings, the puppet config subcommand is improved enough for normal
usage.
Split docs for additional config files out into their own pages in PRM

- Improved google juice! Search for a thing, find the thing.
- Improved browsing via PRM sidebar!
- Versionable info, once some of these finally become superfluous or change
  their behavior.
Correct capitalization in PRM sidebar
Fix regex in file server guide
Add page for csr_attributes.yaml file
Change 3.latest reference links to 3.stable

3.latest should only be used when linking to something that's still in RC; once
a final release with that feature goes out, it should change to stable.
PRM: Add list of pending "directory" pages to sidebar

We're about to add these pages one by one.
PRM: Add page on ssldir
Change wording of location section for config files
PRM: Add hiera.yaml to config file list

These things multiply like little configurable bunnies.
PRM: Add vardir page

Punting a bit on this one, because it's all less important to interact with.
ssldir: make confdir reference platform-agnostic
ssldir: minor edits
PRM: Add confdir page

Mostly about location, link out for everything else.
PRM/rel-notes: Add clientnoop variable from 3.3.0

This got missed because it was a community contribution from before we started
tracking those in jira.
Minor wording change
Split Puppet docs to make 3.5 a new version

The original plan of breaking on major versions no longer makes the sense we
thought it would: we've been more parsimonious with major versions than we
thought, and have made many significant changes in minor versions.
Remove old planning garbage from puppet 3.5 sidebar

We can get it from the puppet 3 one if needed.
Collapse conditional descriptions of things that are old news in 3.5
Add config print and config set pages (links are TODO)