Fix a typo in toolchain_container's README (bazelbuild#983)

docker/toolchain_container/README.md

@@ -1,9 +1,9 @@
 # Bazel toolchain container rules
 
 Rules in this directory provide functionality to build `toolchain_container`s.
-These are containers made up of `lanugage_tool_layer`s. Each `lanugage_tool_layer`
+These are containers made up of `language_tool_layer`s. Each `language_tool_layer`
 produces a `container_image` with a set of debian packages installed.
-A `lanugage_tool_layer` can define any attributes of a `container_image`.
+A `language_tool_layer` can define any attributes of a `container_image`.
 Note these rules depend on `docker/package_managers` rules which in turn 
 require a docker binary to be present and configured properly via
 [docker toolchain rules](https://github.com/nlopezgi/rules_docker/blob/master/toolchains/docker/readme.md#how-to-use-the-docker-toolchain).