fix image location.

[jyao1]

The original image location is invalid.

[ved-rivos]

@jyao1 - this update did not seem necessary as the images render fine and the build process seems to be able to find them correctly. Did you observe an issue?

[jyao1]

Yes, it is a problem.

When you click https://github.com/riscv-non-isa/riscv-iommu/blob/main/src/iommu_intro.adoc or https://github.com/riscv-non-isa/riscv-iommu/blob/main/src/iommu_data_structures.adoc, it reports the image is missing.

[ved-rivos]

@jyao1 I see. You are facing the issue when viewing the .adoc. I will add this update to the PR #441 so we can address it as part of the next specification update.