Add docker context workaround to readme (#749)

* Add docker context workaround to readme

* Update README.md

Co-authored-by: Ryan (hackercat) <me@hackerc.at>

* Fix README

MD031/blanks-around-fences Fenced code blocks should be surrounded by blank lines [

Co-authored-by: Ryan (hackercat) <me@hackerc.at>

README.md

@@ -188,6 +188,16 @@ steps:
 
 If the `path:` value doesn't match the name of the repository, a `MODULE_NOT_FOUND` will be thrown.
 
+## `docker context` support
+
+The current `docker context` isn't respected ([#583](https://github.com/nektos/act/issues/583)).
+
+You can work around this by setting `DOCKER_HOST` before running `act`, with e.g:
+
+```bash
+export DOCKER_HOST=$(docker context inspect --format '{{.Endpoints.docker.Host}}')
+```
+
 # Runners
 
 GitHub Actions offers managed [virtual environments](https://help.github.com/en/actions/reference/virtual-environments-for-github-hosted-runners) for running workflows. In order for `act` to run your workflows locally, it must run a container for the runner defined in your workflow file. Here are the images that `act` uses for each runner type and size: