[main][Docs] Fix spelling errors across documentation (#6649)

Fix various spelling mistakes in the project documentation to improve
clarity and correctness.
- vLLM version: v0.15.0
- vLLM main:
d7e17aaacd

---------

Signed-off-by: SlightwindSec <slightwindsec@gmail.com>

docs/source/developer_guide/feature_guide/quantization.md

@@ -26,7 +26,7 @@ The `create_weights` method is used for weight initialization; the `process_weig
 
 We need to implement the `create_weights`, `process_weights_after_loading`, and `apply` methods for different **layers** (**attention**, **mlp**, **moe**).
 
-**Supplemnet**: When loading the model, the quantized model's description file **quant_model_description.json** needs to be read. This file describes the quantization configuration and parameters for each part of the model weights, for example:
+**Supplement**: When loading the model, the quantized model's description file **quant_model_description.json** needs to be read. This file describes the quantization configuration and parameters for each part of the model weights, for example:
 
 ```json
 {