chore: small docs cleanups in postprocess and zig example (#5955)

Author: prql-bot

prqlc/bindings/prqlc-c/examples/minimal-zig/src/main.zig

@@ -9,8 +9,7 @@ pub fn main() !void {
     const options = prql.Options{
         .format = false,
         .signature_comment = false,
-        //.target = &target,
-        .target = &target
+        .target = &target,
     };
 
     // Compile the PRQL query

prqlc/prqlc/src/sql/pq/postprocess.rs

@@ -1,6 +1,7 @@
 //! An AST pass after compilation to PQ.
 //!
-//! Currently only moves [SqlTransform::Sort]s.
+//! Infers and propagates [SqlTransform::Sort]s through pipelines and assigns
+//! human-readable names to CTEs and relation variables.
 
 use std::collections::{HashMap, HashSet, VecDeque};