Clarified installation instructions between binary package and docker container (#41)

Made the act runner installation instructions a little bit clearer when using docker. This distinction was not immediately clear and caused some confusion.

Co-authored-by: Jason Song <wolfogre@noreply.gitea.com>
Reviewed-on: https://gitea.com/gitea/docs/pulls/41
Reviewed-by: Jason Song <wolfogre@noreply.gitea.com>
Co-authored-by: Matt Van Hest <notusedfordaily@gmail.com>
Co-committed-by: Matt Van Hest <notusedfordaily@gmail.com>

docs/usage/actions/act-runner.md

@@ -50,6 +50,8 @@ docker pull gitea/act_runner:nightly # for the latest nightly build
 
 Configuration is done via a configuration file. It is optional, and the default configuration will be used when no configuration file is specified.
 
+### Binary configuration
+
 You can generate a configuration file by running the following command:
 
 ```bash
@@ -63,6 +65,8 @@ The default configuration is safe to use without any modification, so you can ju
 ./act_runner --config config.yaml [command]
 ```
 
+### Docker configuration
+
 You could also generate config file with docker:
 
 ```bash
@@ -115,7 +119,7 @@ Tokens are valid for registering multiple runners, until they are revoked and re
 
 ### Register the runner
 
-The act runner can be registered by running the following command:
+If this has been installed using the binary package, the act runner can be registered by running the following command:
 
 ```bash
 ./act_runner register
@@ -194,6 +198,8 @@ services:
       - /var/run/docker.sock:/var/run/docker.sock
 ```
 
+When using docker, there is no requirement to enter the container and manually run `./act_runner daemon` command as shown below. Once the container has been started successfully, it will show up as an active runner in your Gitea instance.
+
 ### Configuring cache when starting a Runner using docker image
 
 If you do not intend to use `actions/cache` in workflow, you can ignore this section.