[Tile-serving] Switch2osm rewrite review needed

[Paul Norman]

I've been working on rewriting the switch2osm guides to make use of
openstreetmap-carto, the increased software in PPAs, modern versions of
Postgres, and other improvements

One guide is on loading data into osm2pgsql. I'm working on the next guide
which is rendering from it, or using it with tilemill. At this point, I'd
like some more eyes to review it: http://switch2osm.org/loading-osm-data/

I am quite confident that the command lines given are accurate. Where review
is more useful is the text explaining them, particularly around the
osm2pgsql command line.

The next three guides I want to do are

- Using this DB with TileMill and openstreetmap-carto
- Setting up a rendering server
- Keeping your database up to date

I also need to write an overview, linking them all together.

For the rendering server, I have not decided all the technical options yet,
as renderd, tirex and the mapquest open stack are all non-trivial to setup.
For keeping up to date, I am inclined to use osmupdate, as is done in
furry-sansa (https://github.com/Komzpa/furry-sansa)