a2disconf, a2dismod, a2dissite, a2enconf, a2enmod, a2ensite, a2query: add page (#3609)

pages/linux/a2query.md

@@ -0,0 +1,24 @@
+# a2query
+
+> Retrieve runtime configuration from Apache on Debian-based OSes.
+> More information: <https://manpages.debian.org/buster/apache2/a2query.1.en.html>.
+
+- List enabled Apache modules:
+
+`sudo a2query -m`
+
+- Check if a specific module is installed:
+
+`sudo a2query -m {{module_name}}`
+
+- List enabled virtual hosts:
+
+`sudo a2query -s`
+
+- Display the currently enabled Multi Processing Module:
+
+`sudo a2query -M`
+
+- Display the Apache version:
+
+`sudo a2query -v`