add three types of resets

Author: DininduSenanayake

docs/4.git_model_commands.md

@@ -440,52 +440,48 @@ flowchart LR
     ```bash
     # List all stashes
     git stash list
-    
+
     # Apply stash without removing it
     git stash apply
-    
+
     # Apply a specific stash
     git stash apply stash@{1}
-    
+
     # Create a named stash
     git stash save "WIP: adding UMAP plots"
-    
+
     # Delete all stashes
     git stash clear
     ```
 
 ### 12. `git reset` — Undoing a mistake
 
-Oops — Dr.X accidentally committed a large **matrix.mtx** test file.
-They unstage it first:
-
-```bash
-git reset matrix.mtx
-```
-
-Then remove the bad commit:
-
-```bash
-git reset --soft HEAD^
-```
+Oops — Dr. X accidentally committed a large **matrix.mtx** test file.
 
-If they want to completely delete it (be careful!):
+There are three types of reset:
 
-```bash
-git reset --hard HEAD^
-```
+!!! terminal-2 "`--soft - : Undo commit, keep changes staged"
+    **Use when:** You want to recommit with a better message or add more files.
+    ```bash
+    # Undo last commit, keep changes in staging area
+    git reset --soft HEAD^
+    ```
 
-Reset moves the “HEAD pointer” to a previous commit — like discarding a failed experiment and reverting to known-good results.
+!!! terminal-2 "`--mixed` (default): Undo commit, unstage changes"
+    
+    **Use when:** You want to redo the commit but need to modify files first.
+    ```bash
+    # Undo last commit, move changes back to working directory
+    git reset HEAD^
+    # or
+    git reset --mixed HEAD^
+    ```
 
-<center>
-```mermaid
-%%{init: {'theme': 'base'}}%%
-gitGraph
-  commit id: "Good commit"
-  commit id: "Bad commit" tag: "HEAD"
-  %% reset --hard HEAD^ moves HEAD back one step
-```
-</center>
+!!! terminal-2 "`--hard`: Undo commit, delete changes"
+    ```bash
+    # Undo last commit and DELETE all changes (be careful!)
+    git reset --hard HEAD^
+    ```
 
 
 ## Common Questions