Add cross references for env/cli

Signed-off-by: Mazz Mosley <[email protected]>

docs/reference/docker-compose.md

@@ -87,15 +87,18 @@ relative to the current working directory.
 
 The `-f` flag is optional. If you don't provide this flag on the command line,
 Compose traverses the working directory and its subdirectories looking for a
-`docker-compose.yml` and a `docker-compose.override.yml` file. You must supply
-at least the `docker-compose.yml` file. If both files are present, Compose
-combines the two files into a single configuration. The configuration in the
-`docker-compose.override.yml` file is applied over and in addition to the values
-in the `docker-compose.yml` file.
+`docker-compose.yml` and a `docker-compose.override.yml` file. You must
+supply at least the `docker-compose.yml` file. If both files are present,
+Compose combines the two files into a single configuration. The configuration
+in the `docker-compose.override.yml` file is applied over and in addition to
+the values in the `docker-compose.yml` file.
+
+See also the `COMPOSE_FILE` [environment variable](overview.md#compose-file).
 
 Each configuration has a project name. If you supply a `-p` flag, you can
 specify a project name. If you don't specify the flag, Compose uses the current
-directory name.
+directory name. See also the `COMPOSE_PROJECT_NAME` [environment variable](
+overview.md#compose-project-name)
 
 
 ## Where to go next

docs/reference/overview.md

@@ -32,11 +32,16 @@ Docker command-line client. If you're using `docker-machine`, then the `eval "$(
 
 Sets the project name. This value is prepended along with the service name to the container container on start up. For example, if you project name is `myapp` and it includes two services `db` and `web` then compose starts containers named  `myapp_db_1` and `myapp_web_1` respectively.
 
-Setting this is optional. If you do not set this, the `COMPOSE_PROJECT_NAME` defaults to the `basename` of the current working directory.
+Setting this is optional. If you do not set this, the `COMPOSE_PROJECT_NAME`
+defaults to the `basename` of the project directory. See also the `-p`
+[command-line option](docker-compose.md).
 
 ### COMPOSE\_FILE
 
-Specify the file containing the compose configuration. If not provided, Compose looks for a file named  `docker-compose.yml` in the current directory and then each parent directory in succession until a file by that name is found.
+Specify the file containing the compose configuration. If not provided,
+Compose looks for a file named  `docker-compose.yml` in the current directory
+and then each parent directory in succession until a file by that name is
+found. See also the `-f` [command-line option](docker-compose.md).
 
 ### COMPOSE\_API\_VERSION