fix(docs): replace ambiguous search_value with $1 parameter

SQL examples using undefined 'search_value' variable would cause
"column does not exist" errors if copied verbatim. Changed to $1
placeholder to indicate query parameter usage.

Fixes common issue identified by dual-verification review.

Author: tobyhede

docs/reference/database-indexes.md

@@ -362,7 +362,7 @@ Convert both sides to `jsonb[]` and use the native containment operator:
 ```sql
 SELECT * FROM table_name
 WHERE eql_v2.jsonb_array(encrypted_column) @>
-      eql_v2.jsonb_array(search_value::eql_v2_encrypted);
+      eql_v2.jsonb_array($1::eql_v2_encrypted);
 ```
 
 #### Approach 2: Using Helper Function
@@ -371,7 +371,7 @@ Use the convenience function which handles the conversion internally:
 
 ```sql
 SELECT * FROM table_name
-WHERE eql_v2.jsonb_contains(encrypted_column, search_value::eql_v2_encrypted);
+WHERE eql_v2.jsonb_contains(encrypted_column, $1::eql_v2_encrypted);
 ```
 
 Both approaches produce the same result and use the GIN index.
@@ -383,7 +383,7 @@ Use `EXPLAIN` to verify the GIN index is being used:
 ```sql
 EXPLAIN SELECT * FROM table_name
 WHERE eql_v2.jsonb_array(encrypted_column) @>
-      eql_v2.jsonb_array(search_value::eql_v2_encrypted);
+      eql_v2.jsonb_array($1::eql_v2_encrypted);
 ```
 
 **Expected output:**

docs/reference/index-config.md

@@ -236,7 +236,7 @@ For efficient containment queries on large tables, you can create a GIN index us
 CREATE INDEX idx_encrypted_jsonb ON mytable USING GIN (eql_v2.jsonb_array(encrypted_col));
 
 -- Query using containment (will use the GIN index)
-SELECT * FROM mytable WHERE encrypted_col @> search_value;
+SELECT * FROM mytable WHERE encrypted_col @> $1::eql_v2_encrypted;
 ```
 
 The following helper functions are available for GIN-indexed containment queries:

docs/reference/json-support.md

@@ -115,7 +115,7 @@ ANALYZE examples;
 -- Query using the GIN index
 SELECT * FROM examples
 WHERE eql_v2.jsonb_array(encrypted_json) @>
-      eql_v2.jsonb_array(search_value::eql_v2_encrypted);
+      eql_v2.jsonb_array($1::eql_v2_encrypted);
 ```
 
 See [GIN Indexes for JSONB Containment](./database-indexes.md#gin-indexes-for-jsonb-containment) for complete setup instructions.