LLM: add README.md for Long-Context examples. (#10765)

* LLM: add readme to long-context examples.

* add precision.

* update wording.

* add GPU type.

* add Long-Context example to GPU examples.

* fix comments.

* update max input length.

* update max length.

* add output length.

* fix wording.

python/llm/example/GPU/Long-Context/README.md

@@ -0,0 +1,33 @@
+# Running Long-Context generation using IPEX-LLM on Intel Arc™ A770 Graphics
+
+Long-Context Generation is a critical aspect in various applications, such as document summarization, extended conversation handling, and complex question answering. Effective long-context generation can lead to more coherent and contextually relevant responses, enhancing user experience and model utility.
+
+This folder contains examples of running long-context generation with IPEX-LLM on Intel Arc™ A770 Graphics(16GB GPU memory):
+
+<!-- TODO: Maybe like this after adding more examples:
+- [Single GPU](Single GPU): single GPU examples w & w/o batch.
+- [Multiple GPU](Multiple GPU): multiple GPU examples w & w/o batch. -->
+- [LLaMA2-32K](LLaMA2-32K): examples of running LLaMA2-32K models with INT4/FP8 precision.
+- [ChatGLM3-32K](Chatglm3-32K): examples of running ChatGLM3-32K models with INT4/FP8 precision.
+
+### Maximum Input Length for Different Models with INT4/FP8 Precision.
+
+- **INT4**
+
+    | Model Name | Low Memory Mode | Maximum Input Length | Output Length |
+    | -- | -- | -- | -- |
+    | LLaMA2-7B-32K | Disable | 10K | 512 |
+    |  | Enable | 12K | 512 |
+    | ChatGLM3-6B-32K | Disable | 9K | 512 |
+    |  | Enable | 10K | 512 |
+
+- **FP8**
+
+    | Model Name | Low Memory Mode | Maximum Input Length | Output Length |
+    | -- | -- | -- | -- |
+    | LLaMA2-7B-32K | Disable | 7K | 512 |
+    |  | Enable | 9K | 512 |
+    | ChatGLM3-6B-32K | Disable | 8K | 512|
+    |  | Enable | 9K | 512 |
+
+> Note: If you need to run longer input or use less memory, please set `IPEX_LLM_LOW_MEM=1` to enable **low memory mode**, which will enable memory optimization and may slightly affect the performance.

python/llm/example/GPU/README.md

@@ -12,6 +12,7 @@ This folder contains examples of running IPEX-LLM on Intel GPU:
 - [PyTorch-Models](PyTorch-Models): running any PyTorch model on IPEX-LLM (with "one-line code change")
 - [Speculative-Decoding](Speculative-Decoding): running any ***Hugging Face Transformers*** model with ***self-speculative decoding*** on Intel GPUs
 - [ModelScope-Models](ModelScope-Models): running ***ModelScope*** model with IPEX-LLM on Intel GPUs
+- [Long-Context](Long-Context): running **long-context** generation with IPEX-LLM on Intel Arc™ A770 Graphics.
 
 
 ## System Support