ci: drop custom Cross images

It looks like these aren't needed any more? I'm not sure why to be
honest. I suspect it's because we no longer need asciidoc(tor)? to
generate man pages. And I believe tests that require things like `zstd`
are automatically if `zstd` isn't installed.

1 files changed, 0 insertions, 23 deletions

diff --git a/ci/docker/README.md b/ci/docker/README.md
deleted file mode 100644
index 19913e02..00000000
--- a/ci/docker/README.md
+++ /dev/null
@@ -1,23 +0,0 @@
-These are Docker images used for cross compilation in CI builds (or locally)
-via the [Cross](https://github.com/rust-embedded/cross) tool.
-
-The Cross tool actually provides its own Docker images, and all Docker images
-in this directory are derived from one of them. We provide our own in order to
-customize the environment. For example, we need to install compression tools
-like `xz` so that tests for the `-z/--search-zip` flag are run.
-
-If you make a change to a Docker image, then you can re-build it. `cd` into the
-directory containing the `Dockerfile` and run:
-
-    $ cd x86_64-unknown-linux-musl
-    $ ./build
-
-At this point, subsequent uses of `cross` will now use your built image since
-Docker prefers local images over remote images. In order to make these changes
-stick, they need to be pushed to Docker Hub:
-
-    $ docker push burntsushi/cross:x86_64-unknown-linux-musl
-
-Of course, only I (BurntSushi) can push to that location. To make `cross` use
-a different location, then edit `Cross.toml` in the root of this repo to use
-a different image name for the desired target.