remove too absolute words

Signed-off-by: Alex Chi <iskyzh@gmail.com>

mini-lsm-book/src/00-preface.md

@@ -42,7 +42,7 @@ In this tutorial, we will learn how to build an LSM-Tree-based storage engine in
 
 ## What should you expect from this tutorial...
 
-After learning this course, you should have a deep understanding of how a LSM-based storage system works, gain hands-on experience of designing such systems, and apply what you have learned in your study and career. You will become an expert of LSM storage systems, understand the design tradeoffs in such storage systems, and find optimal ways to design a LSM-based storage system to meet your workload requirements/goals. This is a very in-depth tutorial that covers all the important implementation details and design choices of modern storage systems (i.e., RocksDB) based on the author's experience in several LSM-like storage systems, and you will be able to directly apply what you have learned in both industry and academia.
+After learning this course, you should have a deep understanding of how a LSM-based storage system works, gain hands-on experience of designing such systems, and apply what you have learned in your study and career. You will understand the design tradeoffs in such storage systems and find optimal ways to design a LSM-based storage system to meet your workload requirements/goals. This is a very in-depth tutorial that covers all the important implementation details and design choices of modern storage systems (i.e., RocksDB) based on the author's experience in several LSM-like storage systems, and you will be able to directly apply what you have learned in both industry and academia.
 
 ### Structure
 
@@ -66,9 +66,9 @@ You may access the solution checkpoint repo at [https://github.com/skyzh/mini-ls
 
 ### Feedbacks
 
-Your feedback is greatly appreciated. We have rewritten the whole course from scratch in 2024 based on the feedbacks from the students. We hope you can share your learning experience and help us continuously improve the learning experience. Please join the [Discord community](https://skyzh.dev/join/discord) to share your experience.
+Your feedback is greatly appreciated. We have rewritten the whole course from scratch in 2024 based on the feedbacks from the students. We hope you can share your learning experience and help us continuously improve the tutorial. Welcome to the [Discord community](https://skyzh.dev/join/discord) and share your experience.
 
-The tutorial was originally planned as a general guidance that students start from an empty directory and implement whatever they want based on the specification we had. We had minimal tests that checks if the behavior is correct. However, the original tutorial is too open-ended that caused huge obstacles with the learning experience. As students do not have an overview of the whole system beforehand and the instructions are kind of vague, sometimes it is hard for the students to know why a design decision is made and what they need to achieve a goal. And some part of the course is too compact that it is impossible to deliver expected contents within just one chapter. Therefore, we completely redesigned the course to have a easier learning curve and clearer learning goals. The original one-week tutorial is now split into two weeks (first week on storage format, and second week on deep-dive compaction), with an extra part on MVCC. We hope you find this course interesting and helpful in your study and career. We would like to thank everyone who commented in [Feedback after coding day 1](https://github.com/skyzh/mini-lsm/issues/11) and [Hello, when is the next update plan for the tutorial?](https://github.com/skyzh/mini-lsm/issues/7) -- your feedback greatly helped us improve the course.
+The long story of why we rewrote it: The tutorial was originally planned as a general guidance that students start from an empty directory and implement whatever they want based on the specification we had. We had minimal tests that checks if the behavior is correct. However, the original tutorial is too open-ended that caused huge obstacles with the learning experience. As students do not have an overview of the whole system beforehand and the instructions are kind of vague, sometimes it is hard for the students to know why a design decision is made and what they need to achieve a goal. And some part of the course is too compact that it is impossible to deliver expected contents within just one chapter. Therefore, we completely redesigned the course to have a easier learning curve and clearer learning goals. The original one-week tutorial is now split into two weeks (first week on storage format, and second week on deep-dive compaction), with an extra part on MVCC. We hope you find this course interesting and helpful in your study and career. We would like to thank everyone who commented in [Feedback after coding day 1](https://github.com/skyzh/mini-lsm/issues/11) and [Hello, when is the next update plan for the tutorial?](https://github.com/skyzh/mini-lsm/issues/7) -- your feedback greatly helped us improve the course.
 
 ### License