build: rename Dockerfile to Containerfile

since these files need the -v option that is not present with Docker,
rename the files to Containerfile to avoid confusion.

more info: https://twitter.com/cpuguy83/status/1313523894536429568

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

.github/workflows/release.yaml

@@ -20,8 +20,8 @@ jobs:
       run: |
         ./buildx create --name cross --platform=amd64,arm,arm64,s390x,ppc64le  --use
         ./buildx inspect --bootstrap
-    - name: "Build binaries from Dockerfile.cross"
-      run: ./buildx build -o /tmp --platform=amd64,arm64,arm,s390x,ppc64le -f Dockerfile.cross .
+    - name: "Build binaries from Containerfile.cross"
+      run: ./buildx build -o /tmp --platform=amd64,arm64,arm,s390x,ppc64le -f Containerfile.cross .
     - name: "Create /tmp/artifact"
       run: |
         mkdir -p /tmp/artifact

README.md

@@ -43,11 +43,11 @@ the install script will usually create the device automatically; or
   * manually create the device with the command `mknod /dev/fuse -m 0666 c 10 229` 
 (see [this code](https://github.com/libfuse/libfuse/blob/f0e08cc700d629da2d46def8b620b0ed858cc0d9/util/install_helper.sh#L35))
 
-3. Clone this repository, and switch to the top-level folder containing the file "`Dockerfile.static.ubuntu`";
+3. Clone this repository, and switch to the top-level folder containing the file "`Containerfile.static.ubuntu`";
 
 4. Launch the build with the command (note the single dot `.` at the end): 
 ```
-buildah bud -v $PWD:/build/fuse-overlayfs -t fuse-overlayfs -f ./Dockerfile.static.ubuntu .
+buildah bud -v $PWD:/build/fuse-overlayfs -t fuse-overlayfs -f ./Containerfile.static.ubuntu .
 ```
 
 5. Copy the resulting binary to your host:

tests/alpine.sh

@@ -4,7 +4,7 @@ cd "$(dirname "$0")"
 
 set -ex
 
-docker build -t fuse-overlayfs:alpine -f ../Dockerfile.alpine ..
+docker build -t fuse-overlayfs:alpine -f ../Containerfile.alpine ..
 
 docker run --privileged --rm --entrypoint /unlink.sh -w /tmp \
 	-e EXPECT_UMOUNT_STATUS=1 \