All: upgrade relevanssi plugin to 3.6.2.2

Unpacked from https://github.com/msaari/relevanssi/archive/refs/tags/3.6.2.2.zip
View at https://github.com/msaari/relevanssi/tree/3.6.2.2

This upgrade fixes an error deploying some sites when `WP_LANG`
in stopwords.php is no longer defined globally in the current version of
WordPress.

Author: timmywil

mu-plugins/relevanssi/LICENSE

@@ -0,0 +1,18 @@
+# Relevanssi
+Relevanssi replaces the standard WordPress search with a better search engine, with lots of features and configurable options. You’ll get better results, better presentation of results – your users will thank you.
+
+This is the free version of Relevanssi. There’s also Relevanssi Premium, which has added features, including Multisite support. This free version does not work properly on Multisite. For more information about Premium, see [Relevanssi.com](https://www.relevanssi.com/).
+
+For more information, also see [Relevanssi plugin page at WordPress.org](https://wordpress.org/plugins/relevanssi/).
+
+# Installation
+The easiest way to install is using the WordPress plugin install tools: go to Plugins, choose Add new, search for "Relevanssi" and install.
+
+# FAQ
+For FAQ, see [Relevanssi plugin page](https://wordpress.org/plugins/relevanssi/).
+
+# Support
+For support, post to the [Relevanssi support forum](https://wordpress.org/support/plugin/relevanssi).
+
+# Translations
+Relevanssi translations are handled by the [WordPress translations system](https://translate.wordpress.org/projects/wp-plugins/relevanssi).