The example for enabling IR transmission in `/boot/config.txt` is still using the deprecated `lirc-rpi` overlay. 
The documentation in `/boot/overlays/README` indicates that this overlay has been deprecated in favor of `gpio-ir` / `gpio-ir-tx`.

This updates the actual config.txt to suggest `gpio-ir` instead of `lirc-rpi`.

This reverts commit a0165616.

* Use `&&` instead of `;` in Docker pipeline

* In case of error, `&&` does not continue execution

* Silence shellcheck warning

* SC2086: Double quote to prevent globbing and word splitting.

* Ensure that the configuration file is an absolute path in Docker build

The specific problem is in commit 2ddd7c1, where the passed config file
(using the `-c` option) is now mounted inside the container using the
`--volume src:dest:opt` Docker option.

The problem is that Docker requires absolute paths for mounting single
files inside the container, otherwise it silently tries to mount a volume
name instead as an empty directory. Therefore the Docker build no longer
works with the following invocation forms (relative config-paths):

    ./build-docker.sh -c myconfig
    /path/to/build-docker.sh -c myconfig   # also doesn't work

This commit uses `realpath` (included in coreutils) in the Docker build
script to ensure that the passed configuration file is always an
absolute path before passing it to Docker.

Last commit made the script break on macOS.

From `man sed` (On Linux):

```
       -E, -r, --regexp-extended

              use extended regular expressions in the script (for portability use POSIX -E).
```

This reverts commit 18065049.

In Buster, APT has built‐in support for HTTPS repos (since version 1.5).
The ca-certificates package is already included in the modified file, so
this commit shouldn’t break anything.

In 66731811, README.md’s file mode bits
were changed from 0o644 to 0o755. This commit reverts them back to
0o644.

* bash variables in build-docker.sh are wrapped by curly brackets

* Ensure presence of config file while running build-docker.sh

* Do not assume that build-docker.sh is run from the repository root directory

* Mount config file in predictable location in docker container

Check that file exist before move.

Turning off IPv6 by aliasing `net-pf-10` to `off` does not work anymore.
Also, turning off IPv6 on system level breaks apps depending on IPv6
loopback or IPv6 link-local addresssing and creates issues in both
dual-stack and IPv6-only environments.

Signed-off-by: Ondřej Caletka <ondrej@caletka.cz>

Added a handy message to make it clear that compiling on a 64 bit OS is causing issues. After spending over an hour of troubleshooting think it should be made clearer as it'll affect quite a few users.

With the Qemu version shipped with Debian Stretch, the `man-db` package
being installed for Buster in the image triggers many of these errors:

    qemu: Unsupported syscall: 383

This is a manifestation of the following bug:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=891109

This is resolved in the current Qemu version shipped with Debian Buster.

This reverts commit 3682a747.