docs(ingest): clarify adding source guide (#9161)

metadata-ingestion/adding-source.md

@@ -6,7 +6,7 @@ There are two ways of adding a metadata ingestion source.
 2. You are writing the custom source for yourself and are not going to contribute back (yet).
 
 If you are going for case (1) just follow the steps 1 to 9 below. In case you are building it for yourself you can skip
-steps 4-9 (but maybe write tests and docs for yourself as well) and follow the documentation
+steps 4-8 (but maybe write tests and docs for yourself as well) and follow the documentation
 on [how to use custom ingestion sources](../docs/how/add-custom-ingestion-source.md)
 without forking Datahub.
 
@@ -27,6 +27,7 @@ from `ConfigModel`. The [file source](./src/datahub/ingestion/source/file.py) is
 We use [pydantic](https://pydantic-docs.helpmanual.io) conventions for documenting configuration flags. Use the `description` attribute to write rich documentation for your configuration field.
 
 For example, the following code:
+
 ```python
 from pydantic import Field
 from datahub.api.configuration.common import ConfigModel
@@ -49,12 +50,10 @@ generates the following documentation:
   <img width="70%"  src="https://raw.githubusercontent.com/datahub-project/static-assets/main/imgs/metadata-ingestion/generated_config_docs.png"/>
 </p>
 
-
 :::note
 Inline markdown or code snippets are not yet supported for field level documentation.
 :::
 
-
 ### 2. Set up the reporter
 
 The reporter interface enables the source to report statistics, warnings, failures, and other information about the run.
@@ -71,6 +70,8 @@ some [convenience methods](./src/datahub/emitter/mce_builder.py) for commonly us
 
 ### 4. Set up the dependencies
 
+Note: Steps 4-8 are only required if you intend to contribute the source back to the Datahub project.
+
 Declare the source's pip dependencies in the `plugins` variable of the [setup script](./setup.py).
 
 ### 5. Enable discoverability
@@ -119,37 +120,38 @@ from datahub.ingestion.api.decorators import (
 @capability(SourceCapability.LINEAGE_COARSE, "Enabled by default")
 class FileSource(Source):
    """
-   
-   The File Source can be used to produce all kinds of metadata from a generic metadata events file. 
+
+   The File Source can be used to produce all kinds of metadata from a generic metadata events file.
    :::note
    Events in this file can be in MCE form or MCP form.
    :::
-   
+
    """
 
    ... source code goes here
 
 ```
 
-
 #### 7.2 Write custom documentation
 
-- Create a copy of [`source-docs-template.md`](./source-docs-template.md) and edit all relevant components. 
+- Create a copy of [`source-docs-template.md`](./source-docs-template.md) and edit all relevant components.
 - Name the document as `<plugin.md>` and move it to `metadata-ingestion/docs/sources/<platform>/<plugin>.md`. For example for the Kafka platform, under the `kafka` plugin, move the document to `metadata-ingestion/docs/sources/kafka/kafka.md`.
 - Add a quickstart recipe corresponding to the plugin under `metadata-ingestion/docs/sources/<platform>/<plugin>_recipe.yml`. For example, for the Kafka platform, under the `kafka` plugin, there is a quickstart recipe located at `metadata-ingestion/docs/sources/kafka/kafka_recipe.yml`.
 - To write platform-specific documentation (that is cross-plugin), write the documentation under `metadata-ingestion/docs/sources/<platform>/README.md`. For example, cross-plugin documentation for the BigQuery platform is located under `metadata-ingestion/docs/sources/bigquery/README.md`.
 
 #### 7.3 Viewing the Documentation
 
-Documentation for the source can be viewed by running the documentation generator from the `docs-website` module. 
+Documentation for the source can be viewed by running the documentation generator from the `docs-website` module.
 
 ##### Step 1: Build the Ingestion docs
+
 ```console
 # From the root of DataHub repo
 ./gradlew :metadata-ingestion:docGen
 ```
 
 If this finishes successfully, you will see output messages like:
+
 ```console
 Ingestion Documentation Generation Complete
 ############################################
@@ -170,14 +172,16 @@ Ingestion Documentation Generation Complete
 You can also find documentation files generated at `./docs/generated/ingestion/sources` relative to the root of the DataHub repo. You should be able to locate your specific source's markdown file here and investigate it to make sure things look as expected.
 
 #### Step 2: Build the Entire Documentation
-To view how this documentation looks in the browser, there is one more step. Just build the entire docusaurus page from the `docs-website` module. 
+
+To view how this documentation looks in the browser, there is one more step. Just build the entire docusaurus page from the `docs-website` module.
 
 ```console
 # From the root of DataHub repo
 ./gradlew :docs-website:build
 ```
 
 This will generate messages like:
+
 ```console
 ...
 > Task :docs-website:yarnGenerate
@@ -219,15 +223,15 @@ BUILD SUCCESSFUL in 35s
 36 actionable tasks: 16 executed, 20 up-to-date
 ```
 
-After this you need to run the following script from the `docs-website` module. 
+After this you need to run the following script from the `docs-website` module.
+
 ```console
 cd docs-website
 npm run serve
 ```
 
-Now, browse to http://localhost:3000 or whichever port npm is running on, to browse the docs. 
-Your source should show up on the left sidebar under `Metadata Ingestion / Sources`. 
-
+Now, browse to http://localhost:3000 or whichever port npm is running on, to browse the docs.
+Your source should show up on the left sidebar under `Metadata Ingestion / Sources`.
 
 ### 8. Add SQL Alchemy mapping (if applicable)