Fix documentation (#1796)
Fix documentation (#1796)

1. [x] Describe in common words what is the purpose of this change, related
   Github Issues, and highlight important implementation aspects.
   
   Fixed the misprint

2. [x] Please put changelog entries **in the description of this Pull Request**
   if knowledge of this change could be valuable to users. No need to put the
   entries to the changelog directly, they will be transferred to the changelog
   files(`CHANGELOG_VULKANO.md` and `CHANGELOG_VK_SYS.md`)
   by maintainers right after the Pull Request merge.

    * Entries for Vulkano changelog:
        - `**Breaking** Breaking entry description.`
        - `Non-breaking entry description.`...

    * Entries for VkSys changelog:
        - `Entry 1.`
        - `Entry 2.`...

3. [x] Run `cargo fmt` on the changes.

4. [x] Make sure that the changes are covered by unit-tests.

5. [x] Update documentation to reflect any user-facing changes - in this repository.
vulkano-rs/vulkano