add docs for db and redis

src/content/docs/processors/db/query.md

@@ -0,0 +1,19 @@
+---
+title: Query
+sidebar:
+    order: 1
+---
+The `db.query` processor will issue a query to the specified module and return the result to the next processor in line.
+
+- **type**: `db.query`
+- **params**:
+    - **module**: the id of the [module](/concepts/modules) to issue query to.
+    - **query**: the query to execute. 
+### Example
+Issue a `SELECT` statement to a module with id `sqlite`.
+```
+- type: db.query
+  params:
+    module: sqlite
+    query: "SELECT * from users;"
+```