misc: Fix spelling issues

Misspellings were identified by:
  https://github.com/marketplace/actions/check-spelling

* Initial corrections based on forbidden patterns from the action
* Additional corrections by Google Chrome auto-suggest
* Some manual corrections
* Adding markdown bullets to readme credits section

Signed-off-by: Josh Soref <2119212+jsoref@users.noreply.github.com>

docs/iommu.md

@@ -39,7 +39,7 @@ Another reason for having a virtual IOMMU is to allow passing physical devices
 from the host through multiple layers of virtualization. Let's take as example
 a system with a physical IOMMU running a VM with a virtual IOMMU. The
 implementation of the virtual IOMMU is responsible for updating the physical
-DMA Remapping table (DMAR) everytime the DMA mapping changes. This must happen
+DMA Remapping table (DMAR) every time the DMA mapping changes. This must happen
 through the VFIO framework on the host as this is the only userspace interface
 to interact with a physical IOMMU.
 
@@ -124,7 +124,7 @@ On AArch64 architecture, the virtual IOMMU can still be used even if ACPI is not
 enabled. But the effect is different with what the aforementioned test showed.
 
 When ACPI is disabled, virtual IOMMU is supported through Flattened Device Tree
-(FDT). In this case, the guest kernel can not tell which device should be
+(FDT). In this case, the guest kernel cannot tell which device should be
 IOMMU-attached and which should not. No matter how many devices you attached to
 the virtual IOMMU by setting `iommu=on` option, all the devices on the PCI bus
 will be attached to the virtual IOMMU (except the IOMMU itself). Each of the