Improve documentation of task hash (#5749)

Signed-off-by: Ben Sherman <[email protected]>

docs/cache-and-resume.md

@@ -22,10 +22,10 @@ The task hash is computed from the following metadata:
 - Task {ref}`environment modules <process-module>` (if applicable)
 - Task {ref}`Conda environment <process-conda>` (if applicable)
 - Task {ref}`Spack environment <process-spack>` and {ref}`CPU architecture <process-arch>` (if applicable)
-- Task {ref}`process-ext` directive (if applicable)
 - Task {ref}`inputs <process-input>`
 - Task {ref}`script <process-script>`
 - Any global variables referenced in the task script
+- Any task {ref}`process-ext` properties referenced in the task script
 - Any {ref}`bundled scripts <bundling-executables>` used in the task script
 - Whether the task is a {ref}`stub run <process-stub>`
 - Task attempt