Improve formating and fix typo

Improved Build Job descriptions

Only push on 'main' branch

Fix build ...

The Docker Hub build system runs on Ubuntu Xenial containers.
Xenial's git is 2.7.4, which does not know the `-P` flag yet.

Checkout the repository with git ...

This changes the build process even further. Instead
f using `wget` to fetch the current code, `git` is used.
This allows for faster switching between branches,
because only the differences between them have to be
fetched from the server.

But the main advantage is that the build cache can
finally be used as designed by Docker. Repetitive
builds are very fast now. This is also true between
branches and tags, as long as the `requirements.txt`
file doesn't change.

externalize netbox download with wget

Fix caching in build.sh

Fix apt-get detection

Only build the master branch to speed up the test

Try to get PR builds working

Refactor to multistage builds ...

This commit introduces a huge change in the build process.

What changed:

- Dockerfile.ldap was integrated into Dockerfile as a seperate
  [build stage][multistage-build].
- All the build scripts were refactored according to this.
- The `docker-compose.yml` file was adjusted likewise.
- The main build script, `/build.sh`, now always builds all
  targets (formerly called variants).
- The minimal requirements for Docker and docker-compose
  have increased.
- The build on hub.docker.com must be adjusted.

This change should also fix #156 permanently.

[multistage-build]: https://docs.docker.com/develop/develop-images/multistage-build/

Prepare Version 0.18.2

Fix #165

prepare 0.18.1

Merge branch 'fix-160'

fix typo

Adds a hyperlink for the #netbox-docker channel

Prepare Version 0.18.0

Introduce $SKIP_SUPERUSER ...

This adds a new variable to skip the creation of the superuser.
That is useful for LDAP and for production environments.

Fixes #160

Merge branch 'axarriola-master'

Reformat initializers and add some IPv6 examples

Add missing `break`

Merge branch 'master' of https://github.com/axarriola/netbox-docker into axarriola-master

More typos. Tested all changes.

Fixing typos.

Merge branch 'master' of https://github.com/netbox-community/netbox-docker

Merge pull request #162 from netbox-community/cleanup ...

Remove debug statement

Remove debug statement

Merge pull request #161 from netbox-community/fix-platform-initializer ...

Updating the initializer platform examples

Updating the initializer platform examples ...

rpc client was removed from netbox