Document new checkout method key (#9611)

* Update checkout step with method key

* fix some linter errors

* Update docs/reference/modules/ROOT/pages/configuration-reference.adoc

Co-authored-by: Rosie Yohannan <[email protected]>

* Update docs/reference/modules/ROOT/pages/configuration-reference.adoc

Co-authored-by: Rosie Yohannan <[email protected]>

---------

Co-authored-by: Rosie Yohannan <[email protected]>

Author: anthony-j-castro

docs/guides/modules/orchestrate/pages/pipeline-variables.adoc

@@ -116,7 +116,7 @@ Refer to the xref:toolkit:api-developers-guide.adoc#getting-started-with-the-api
 [#passing-parameters-when-triggering-pipelines-using-the-circleci-web-app]
 === Passing parameters when triggering pipelines using the CircleCI web app
 
-In addition to using the API, you can also trigger a pipeline with parameters from the CircleCI web app. If you pass a parameter when triggering a pipeline from the web app, and the parameter has not been declared in the configuration file, the pipeline will fail with the error `Unexpected argument(s)`.
+In addition to using the API, you can also trigger a pipeline with parameters from the CircleCI web app. If you pass a parameter when triggering a pipeline, and the parameter has not been declared in the configuration file, the pipeline will fail with the error `Unexpected argument(s)`.
 
 . Use the project filter to select the desired project.
 . Use the branch filter to select the branch on which you want to run the new pipeline.
@@ -140,7 +140,7 @@ The remaining configuration is processed, element parameters are resolved, type-
 [#the-scope-of-parameters-in-configuration]
 == The scope of parameters in configuration
 
-Pipeline parameters can only be resolved in the `.circleci/config.yml` file in which they are declared. Pipeline parameters are not available in orbs, including orbs declared locally in your `.circleci/config.yml` file. This is because access to pipeline scope in orbs would break encapsulation and create a hard dependency between the orb and the calling configuration. This would potentially create a surface area of vulnerability, increasing security risks.
+Pipeline parameters can only be resolved in the `.circleci/config.yml` file in which they are declared. Pipeline parameters are not available in orbs, including orbs declared locally in your `.circleci/config.yml` file. Access to pipeline scope in orbs would break encapsulation and create a hard dependency between the orb and the calling configuration. This would potentially create a surface area of vulnerability, increasing security risks.
 
 [#element-parameter-scope]
 === Element parameter scope

docs/reference/modules/ROOT/pages/configuration-reference.adoc

@@ -1667,33 +1667,17 @@ workflows:
 [#checkout]
 === *`checkout`*
 
-****
-*Blobless clones*
-
-A "blobless" strategy is being rolled out to help improve the performance of code checkouts from Git source code hosts.
-
-Blobless clones reduce the amount of data fetched from the remote, by asking the remote to filter out objects that are not attached to the current commit.
-
-While this improves performance in most cases, if a downstream step requires those objects to exist for scanning or comparisons, it can cause failures. To work around these potential problems, a fetch directly after a checkout will ensure the required data is available:
-
-[,yml]
-----
-jobs:
-  build:
-    docker:
-      - image: cimg/go:1.24.2
-    steps:
-      - checkout
-      - run: git fetch
-----
-****
-
 A special step used to check out source code to the configured `path` (defaults to the `working_directory`). The reason this is a special step is because it is more of a helper function designed to simplify the process of checking out code. If you require doing git over HTTPS you should not use this step as it configures git to checkout over SSH.
 
 [cols="1,1,1,2", options="header"]
 |===
 | Key | Required | Type | Description
 
+| `method`
+| N
+| String
+| Checkout method. Valid options include `blobless` and `full`. (default: `full`)
+
 | `path`
 | N
 | String
@@ -1721,6 +1705,39 @@ jobs:
 
 The checkout command automatically adds the required authenticity keys for interacting with GitHub and Bitbucket over SSH. These keys are detailed further in the xref:guides:integration:github-integration.adoc#establish-the-authenticity-of-an-ssh-host[integration guide]. This guide is also helpful if you wish to implement a custom checkout command.
 
+You can specify a checkout strategy by using the `method` key. CircleCI supports full clones or blobless clones. Blobless clones reduce the amount of data fetched from the remote by asking the remote to filter out objects that are not attached to the current commit.
+
+*Example:*
+
+[,yml]
+----
+jobs:
+  build:
+    docker:
+      - image: cimg/go:1.24.2
+    steps:
+      - checkout:
+          method: blobless
+----
+
+[NOTE]
+====
+In certain cases, we will fall back to a full checkout even though blobless was specified. This will occur if Git and SSH clients are not available in the current environment, or if Git version 2.41.0 is installed which contained a link:https://lore.kernel.org/git/[email protected]/[known issue] for blobless clones.
+====
+
+If a downstream step requires those objects to exist for scanning or comparisons, a blobless clone can cause failures. In that case, you can specify a full checkout as shown in the following example:
+
+[,yml]
+----
+jobs:
+  build:
+    docker:
+      - image: cimg/go:1.24.2
+    steps:
+      - checkout:
+          method: full
+----
+
 CircleCI does not check out submodules. If your project requires submodules, add `run` steps with appropriate commands as shown in the following example:
 
 [,yml]