fix: contextDir documentation (fabric8io#1193)

src/main/asciidoc/inc/build/_configuration.adoc

@@ -25,6 +25,9 @@ https://docs.docker.com/engine/reference/api/docker_remote_api_v1.24/#build-imag
 | *cleanup*
 | Cleanup dangling (untagged) images after each build (including any containers created from them). Default is `try` which tries to remove the old image, but doesn't fail the build if this is not possible because e.g. the image is still used by a running container. Use `remove` if you want to fail the build and `none` if no cleanup is requested.
 
+| [[context-dir]]*contextDir*
+| Path to a directory used for the build's context. You can specify the `Dockerfile` to use with *dockerFile*, which by default is the Dockerfile found in the `contextDir`. The Dockerfile can be also located outside of the `contextDir`, if provided with an absolute file path. See <<external-dockerfile, External Dockerfile>> for details.
+
 | <<misc-startup, *cmd*>>
 | A command to execute by default (i.e. if no command is provided when a container for this image is started). See <<misc-startup,Startup Arguments>> for details.
 
@@ -34,9 +37,8 @@ https://docs.docker.com/engine/reference/api/docker_remote_api_v1.24/#build-imag
 | *dockerFile*
 | Path to a `Dockerfile` which also triggers _Dockerfile mode_. See <<external-dockerfile, External Dockerfile>> for details.
 
-| *dockerFileDir*
-| Path to a directory holding a `Dockerfile` and switch on _Dockerfile mode_. See <<external-dockerfile, External Dockerfile>> for details.
-
+| *dockerFileDir* (_deprecated_ in favor of *<<context-dir, contextDir>>*)
+| Path to a directory holding a `Dockerfile` and switch on _Dockerfile mode_. See <<external-dockerfile, External Dockerfile>> for details. _This option is deprecated in favor of _contextDir_ and will be removed for the next major release_.
 
 | *dockerArchive*
 | Path to a saved image archive which is then imported. See <<external-dockerfile, Docker archive>> for details.

src/main/asciidoc/inc/build/_overview.adoc

@@ -12,9 +12,9 @@ When using this mode, the Dockerfile is created on the fly with all instructions
 Alternatively an external Dockerfile template or Docker archive can be used. This mode is switched on by using one of these three configuration options within
 
 * *contextDir* specifies docker build context if an external dockerfile is located outside of Docker build context. If not specified, Dockerfile's parent directory is used as build context.
-* *dockerFile* specifies a specific Dockerfile path.
+* *dockerFile* specifies a specific Dockerfile path. The Docker build context directory is set to `contextDir` if given. If not the directory by default is the directory in which the Dockerfile is stored.
 * *dockerArchive* specifies a previously saved image archive to load directly. Such a tar archive can be created with `docker save`. If a `dockerArchive` is provided, no `dockerFile` or `dockerFileDir` must be given.
-* *dockerFileDir* (*deprecated*, use *contextDir*) specifies a directory containing a Dockerfile that will be used to create the image. The name of the Dockerfile is `Dockerfile` by default but can be also set with the option `dockerFile` (see below).
+* *dockerFileDir* (_deprecated_, use *contextDir*) specifies a directory containing a Dockerfile that will be used to create the image. The name of the Dockerfile is `Dockerfile` by default but can be also set with the option `dockerFile` (see below).
 
 All paths can be either absolute or relative paths (except when both `dockerFileDir` and `dockerFile` are provided in which case `dockerFile` must not be absolute). A relative path is looked up in `${project.basedir}/src/main/docker` by default. You can make it easily an absolute path by using `${project.basedir}` in your configuration.