Add docs migration banner (#6853)

Author: christopher-hakkaart

docs/_static/theme.css

@@ -244,3 +244,13 @@ div.deprecated p:first-child::before     { color: #C3514D; }
     font-size: 0.7rem;
     margin-left: 0.5rem;
 }
+
+/* Site-wide announcement banner */
+.admonition.site-banner {
+    background: #E2F7F3;
+    border-left: none;
+}
+
+.admonition.site-banner .admonition-title {
+    background: #0CAE8E;
+}

docs/_templates/layout.html

@@ -1,5 +1,13 @@
 {% extends "!layout.html" %}
 
+{% block document %}
+    <div class="admonition site-banner">
+        <p class="admonition-title">Nextflow documentation is migrating</p>
+        <p>Nextflow documentation is being migrated to <a href="https://docs.seqera.io/nextflow/">docs.seqera.io/nextflow</a>. This site will remain available throughout the migration.</p>
+    </div>
+    {{ super() }}
+{% endblock %}
+
 {% block sidebartitle %}
     {{ super() }}
     {%- set version_selected = "stable" -%}

docs/reference/config.md

@@ -113,7 +113,7 @@ The following settings are available:
 : The AWS Batch [Execution Role](https://docs.aws.amazon.com/batch/latest/userguide/execution-IAM-role.html) ARN that needs to be used to execute the Batch Job. It is mandatory when using AWS Fargate.
 
 `aws.batch.forceGlacierTransfer`
-: :::{versionadded 26.04.0}
+: :::{versionadded} 26.04.0 
   :::
 : When `true`, add the `--force-glacier-transfer` flag to AWS CLI S3 download commands (default: `false`).
 : This option is needed when staging directories that have been restored from [S3 Glacier](https://aws.amazon.com/s3/storage-classes/glacier/). It does not restore objects from Glacier.