chore(search): update README to add some references for KQIR (#2581)

Author: PragmaTwice

src/search/README.md

@@ -1,27 +1,34 @@
-## KQIR: Kvrocks Query Intermediate Representation
+## KQIR (a.k.a. Kvrocks Search): Kvrocks Query Intermediate Representation
 
 Here, *KQIR* refers to both
 - the multiple-level *query intermediate representation* for Apache Kvrocks, and
 - the *architecture and toolset* for the query optimization and execution.
 
+Note that when interacting with users, we also refer to KQIR as *Kvrocks Search* to prevent overwhelming with excessive technical information.
+
 ### Architecture
 
 ![Architecture of KQIR](../../assets/KQIR.png)
 
 ### Components
 
-- User Interface: both SQL and Redis Query syntax is supported to be the frontend language of KQIR
+- User Interface: both SQL and RediSearch Query syntax is supported to be the frontend language of KQIR
   - SQL Parser: A parser that accepts an extended subset of MySQL syntax
-  - Redis Query Parser: A parser that accepts [Redis query syntax](https://redis.io/docs/latest/develop/interact/search-and-query/advanced-concepts/query_syntax/) (only DIALECT 2 or greater is planned to be supported)
+  - Redis Query Parser: A parser that accepts [RediSearch query syntax](https://redis.io/docs/latest/develop/interact/search-and-query/advanced-concepts/query_syntax/) (only DIALECT 2 or greater is planned to be supported)
 - KQIR: a multiple level query intermediate representation, currently including two levels (syntactical IR and planning IR)
   - Syntactical IR: A high level IR that syntactically represents the query language
   - Planning IR: A low level IR that represents plan operators for query execution
 - KQIR passes: analysis and transformation procedures on KQIR
   - Semantic Checker: to check if there is any semantic errors in the IR
-  - Expression Passes: passes for query expressions, especially for logical expressions
-  - Numeric Passes: passes for numeric & arithmetic properties
-  - Plan Passes: passes on the plan operators
+  - Expression Passes: passes for query expressions, especially for logical/boolean expressions
+  - Numeric Passes: passes for numeric & arithmetic expressions utilizing math properties
+  - Planning Passes: passes on the plan operators for scheduling a better execution plan
   - Pass Manager: to manage the pass execution sequence and order
-  - Cost Model: to analyze the cost for the current plan, used by some plan passes
-- Plan Executor: a component for query execution via iterator model
+  - Cost Model: to analyze the cost for the current plan, used by some planning passes
+- Plan Executor: a component for query execution via the iterator model
 - Indexer: to perform the indexing for various types of fields during data changes
+
+### References
+
+- [KQIR: a query engine for Apache Kvrocks that supports both SQL and RediSearch queries](https://kvrocks.apache.org/blog/kqir-query-engine)
+- [Index encoding format for Kvrocks Search](https://kvrocks.apache.org/community/kvrocks-search-index-encoding)