Config: classic mode: adding index page

Signed-off-by: Lynette Miles <[email protected]>

Author: esmerel

administration/configuring-fluent-bit/classic-mode.md

@@ -0,0 +1,16 @@
+# Configure Fluent Bit using classic mode
+
+Fluent Bit classic mode configuration will be deprecated at the end of 2026.
+
+Classic mode is a custom configuration model for Fluent Bit. It's more limited than
+the [YAML configuration mode](../configuring-fluent-bit/yaml.md), and doesn't have
+the more extensive feature support the YAML configuration has. Classic mode basic design only supports grouping sections with key-value pairs and lacks the ability to handle sub-sections or complex data structures like lists.
+
+Learn more about classic mode:
+
+- [Format and schema](./classic-mode/format-schema.md)
+- [Variables](./classic-mode/variables.md)
+- [Configuration file](./classic-mode/configuration-file.md)
+- [Commands](./classic-mode/commands.md)
+- [Upstream servers](./classic-mode/upstream-servers.md)
+- [Record accessor syntax](./classic-mode/record-accessor.md)