Document PIPELINES_FEATURE_EXPERIMENT_GENERATE_ALL_STACKS (#2866)

Author: Resonance1584

docs/2.0/reference/pipelines/feature-flags.md

@@ -11,10 +11,7 @@ Pipelines supports optional feature flags that allow you to enable or disable sp
 Enables all Pipelines experiment flags.
 </li>
 <li>
-**Default Value in Pipelines GitHub v3/GitLab v1**: Disabled
-</li>
-<li>
-**Default Value in Pipelines GitHub v4+/GitLab v2+**: Enabled
+**Default Value: Disabled**
 </li>
 <li>
 **How to Enable**: Set to `"true"`
@@ -79,6 +76,19 @@ We do not recommend enabling this feature by default as it removes the guarantee
 </li>
 </ul>
 
+#### `PIPELINES_FEATURE_EXPERIMENT_GENERATE_ALL_STACKS`
+<ul>
+<li>
+Causes Pipelines to generate all stacks before running a plan or apply operation. This ensures that any stacks that are dependencies of units outside of the current stack or unit are available during the execution.
+</li>
+<li>
+**Default Value**: Disabled
+</li>
+<li>
+**How to Enable**: Set to `"true"`
+</li>
+</ul>
+
 #### `PIPELINES_FEATURE_EXPERIMENT_IGNORE_UNITS_WITHOUT_ENVIRONMENT`
 <ul>
 <li>