Fix documentation comments in `vk::buffer`

This section in the comments for `copy_to_image` in `vk::buffer` needs to remove this unfinished sentence. Additionally adding some grammatical fixes with some parts of these comments.

https://github.com/engine3d-dev/vulkan-cpp/blob/eeeea0b487dbf7369a129b0d31be6687bc1ed850/vulkan-cpp/buffer.cppm#L217