Add doc about shm size

docs/contents/workers/yaml.md

@@ -87,6 +87,7 @@ include:
     - `command`
     : Custom command line to be used when launching the Docker container for
     this Worker. By default, the command specified in the Dockerfile will be used.
+    - `shm_size`: Size of the available shared memory in `/dev/shm`. The default value is `64M`, but when training machine learning models an increase might be necessary. The given value must be either an integer, or an integer followed by a unit (`b` for bytes, `k` for kilobytes, `m` for megabytes and `g` for gigabytes). If no unit is specified, the default unit is `bytes`. See the [Docker documentation](https://docs.docker.com/engine/reference/run/#runtime-constraints-on-resources).
     - `environment`
     : Mapping of string keys and string values to define environment variables to be
 set when the Docker image runs.
@@ -302,6 +303,7 @@ workers:
       build: project/Dockerfile
       image: hub.docker.com/project/image:tag
       command: python mysuperscript.py --blabla
+      shm_size: 128m
       environment:
         TOKEN: deadBeefToken
     configuration: