docs(tfmigrate): remove dead --all flag, clarify --migration path is migration_dir-relative

Follow-up to the preceding fix commit: `migrate list --all` never had any
effect (removed from the CLI), and `--migration <path>` needs to be
relative to migration_dir, not the component directory, to avoid the
double-prefixing bug that commit fixed.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: osterman

website/docs/cli/commands/terraform/terraform-migrate-apply.mdx

@@ -42,7 +42,7 @@ Atmos runs the same component preparation as `plan`: auth, source provisioning,
   <dd>Identity to authenticate before resolving the component and running `tfmigrate apply`. Environment variable: `ATMOS_IDENTITY`.</dd>
 
   <dt>`--migration`</dt>
-  <dd>Path to a single `tfmigrate` migration file. Omit this flag to let `tfmigrate` run history mode. Single-file reruns are not inherently idempotent.</dd>
+  <dd>Path to a single `tfmigrate` migration file, relative to `migration_dir` (defaults to `./migrations` when that directory exists in the component, otherwise the component root) - do not include that prefix. Omit this flag to let `tfmigrate` run history mode. Single-file reruns are not inherently idempotent.</dd>
 
   <dt>`--tfmigrate-config`</dt>
   <dd>Override the `tfmigrate` config path. When omitted, `tfmigrate` uses its own default discovery, including `.tfmigrate.hcl`.</dd>

website/docs/cli/commands/terraform/terraform-migrate-list.mdx

@@ -45,9 +45,6 @@ atmos terraform migrate list [component] [options]
   <dt>`--query`</dt>
   <dd>Filter component instances with a YQ expression.</dd>
 
-  <dt>`--all`</dt>
-  <dd>List all component instances in all stacks.</dd>
-
   <dt>`--format` / `-f`</dt>
   <dd>Output format. Supported values: `table`, `json`, `yaml`, `csv`, `tsv`.</dd>
 
@@ -81,10 +78,10 @@ Show history keys for matching components:
 atmos terraform migrate list --query '.settings.requires_migration == true' --columns component --columns stack --columns history_key
 ```
 
-Output JSON for automation:
+Output JSON for automation (no `[component]` argument lists every component in every stack):
 
 ```shell
-atmos terraform migrate list --all --format json
+atmos terraform migrate list --format json
 ```
 
 ## Output Columns

website/docs/cli/commands/terraform/terraform-migrate-plan.mdx

@@ -40,7 +40,7 @@ atmos terraform migrate plan [component] -s <stack> [options]
   <dd>Identity to authenticate before resolving the component and running `tfmigrate plan`. Environment variable: `ATMOS_IDENTITY`.</dd>
 
   <dt>`--migration`</dt>
-  <dd>Path to a single `tfmigrate` migration file. Omit this flag to let `tfmigrate` run history mode.</dd>
+  <dd>Path to a single `tfmigrate` migration file, relative to `migration_dir` (defaults to `./migrations` when that directory exists in the component, otherwise the component root) - do not include that prefix. Omit this flag to let `tfmigrate` run history mode.</dd>
 
   <dt>`--tfmigrate-config`</dt>
   <dd>Override the `tfmigrate` config path. When omitted, `tfmigrate` uses its own default discovery, including `.tfmigrate.hcl`.</dd>