Adding required Docker version to README and minor changes

README.md

@@ -43,7 +43,8 @@ This project is developed and maintained by the [Tools team][team].
 One of these container engines is required:
 
 - [Docker](https://www.docker.com/). Note that on Linux non-sudo users need to be in the
-  `docker` group. Read the official [post-installation steps][post].
+  `docker` group. Read the official [post-installation steps][post]. Requires version
+  1.24 or later.
 
 [post]: https://docs.docker.com/install/linux/linux-postinstall/
 

src/docker.rs

@@ -17,8 +17,6 @@ const DOCKER: &str = "docker";
 pub fn docker_command(container_engine: &str, subcommand: &str) -> Command {
     let mut docker = Command::new(container_engine);
     docker.arg(subcommand);
-
-    // We always add the `---userns host` flag for compatibility with Podman.
     docker.args(&["--userns", "host"]);
     docker
 }

src/main.rs

@@ -329,7 +329,7 @@ impl Toml {
         }
     }
 
-        /// Returns the `target.{}.container_engine` part of `Cross.toml`
+    /// Returns the `target.{}.container_engine` part of `Cross.toml`
     pub fn container_engine(&self, target: &Target) -> Result<Option<String>> {
         let triple = target.triple();