examples: fix typo in imatrix/README.md (#11884)

* simple typo fixed

* Update examples/imatrix/README.md

---------

Co-authored-by: Tobias Bergmann <tobias.bergmann@gmx.de>
Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

examples/imatrix/README.md

@@ -1,6 +1,6 @@
 # llama.cpp/examples/imatrix
 
-Compute an importance matrix for a model and given text dataset. Can be used during quantization to enchance the quality of the quantized models.
+Compute an importance matrix for a model and given text dataset. Can be used during quantization to enhance the quality of the quantized models.
 More information is available here: https://github.com/ggml-org/llama.cpp/pull/4861
 
 ## Usage