[chore] update cmd/builder documentation for docker image release (op…

…en-telemetry#11480)

since
open-telemetry/opentelemetry-collector-releases#671
was merged into releases repository, docker images will be published
starting with ocb version 0.112.0

This reverts commit 8c4cfe5.

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description
update documentation for cmd/builder to include docker release
information
<!-- Issue number if applicable -->
#### Link to tracking issue
Relates to
open-telemetry#5712
Documentation for
open-telemetry/opentelemetry-collector-releases#671

<!--Describe what testing was performed and which tests were added.-->
#### Testing
n/a
<!--Describe the documentation added.-->
#### Documentation
README.md and release.md
<!--Please delete paragraphs that you did not use before submitting.-->

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

cmd/builder/README.md

@@ -57,11 +57,34 @@ $ /tmp/dist/otelcol-custom --config=/tmp/otelcol.yaml
 
 ## Installation
 
-There are two supported ways to install the builder: via the official releases (recommended) and through `go install`.
+There are three supported ways to install the builder:
+1. Via official release Docker images (recommended)
+2. Via official release binaries (recommended)
+3. Through `go install` (not recommended)
 
-### Official releases
+### Official release Docker image
 
-This is the recommended installation method. Download the binary for your respective platform from the ["Releases"](https://github.com/open-telemetry/opentelemetry-collector-releases/releases?q=cmd/builder) page.
+You will find the official docker images at [DockerHub](https://hub.docker.com/r/otel/opentelemetry-collector-builder). 
+
+Pull the image via tagged version number (e.g. v0.110.0) or 'latest'. You may also specify platform, although Docker will handle this automatically as it is a multi-platform build.
+
+```
+docker pull otel/opentelemetry-collector-builder:latest
+```
+
+The included builder configuration file/manifest should be replaced by mounting a file from your local filesystem to the docker container; the default location is `/build/builder-config.yaml`. If you mount a file at a different location inside the container, your `builder.config.yaml` must be specified as a command line argument to ocb. Additionally, the output folder must also be mounted from your local system to the docker container. This output directory must be specified in your `builder-config.yaml` file as it cannot be set via the command-line arguments.
+
+Assuming you are running this image in your working directory, have a `builder-config.yaml` file located in this folder, the `dist.output_path` item inside your `builder-config.yaml` is set to `./otelcol-dev`, and you wish to output the binary/go module files to a folder named `output`, the command would look as follows:
+
+```
+docker run -v "$(pwd)/builder-config.yaml:/build/builder-config.yaml" -v "$(pwd)/output:/build/otelcol-dev" otel/opentelemetry-collector-builder:latest
+```
+
+Additional arguments may be passed to ocb on the command line as specified below, but if you wish to do this, you must make sure to pass the `--config` argument, as this is specified as an additional `CMD`, not an entrypoint. 
+
+### Official release binaries 
+
+This is the recommended installation method for the binary. Download the binary for your respective platform from the ["Releases"](https://github.com/open-telemetry/opentelemetry-collector-releases/releases?q=cmd/builder) page.
 
 ### `go install`
 

docs/release.md

@@ -91,6 +91,8 @@ The last step of the release process creates artifacts for the new version of th
 
     3. build and release ocb binaries under a separate tagged Github release, e.g. `cmd/builder/v0.85.0`
 
+    4. build and push ocb Docker images to `https://hub.docker.com/r/otel/opentelemetry-collector-builder` and the GitHub Container Registry within the releases repository
+
 ## Troubleshooting
 
 1. `unknown revision internal/coreinternal/v0.85.0` -- This is typically an indication that there's a dependency on a new module. You can fix it by adding a new `replaces` entry to the `go.mod` for the affected module.