[Docs] Only check the specific module during docc verification (#4)

[Docs] Only check the specific module during docc verification

## Summary

Only verify the provided product instead of checking them all, which would include dependencies.

## Test Plan

Ran soundness locally and verified it still works.


Reviewed by: simonjbeaumont

Builds:
     ✔︎ pull request validation (5.8) - Build finished. 
     ✔︎ pull request validation (5.9) - Build finished. 
     ✔︎ pull request validation (nightly) - Build finished. 
     ✔︎ pull request validation (soundness) - Build finished. 

#4

Author: czechboy0

scripts/check-for-docc-warnings.sh

@@ -19,10 +19,14 @@ log() { printf -- "** %s\n" "$*" >&2; }
 error() { printf -- "** ERROR: %s\n" "$*" >&2; }
 fatal() { error "$@"; exit 1; }
 
+log "Checking required environment variables..."
+test -n "${DOCC_TARGET:-}" || fatal "DOCC_TARGET unset"
+
 CURRENT_SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 REPO_ROOT="$(git -C "${CURRENT_SCRIPT_DIR}" rev-parse --show-toplevel)"
 
 swift package --package-path "${REPO_ROOT}" plugin generate-documentation \
+  --product "${DOCC_TARGET}" \
   --analyze \
   --level detailed \
   --warnings-as-errors \

scripts/soundness.sh

@@ -20,6 +20,7 @@ fatal() { error "$@"; exit 1; }
 
 CURRENT_SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 NUM_CHECKS_FAILED=0
+export DOCC_TARGET=OpenAPIRuntime
 
 SCRIPT_PATHS=(
   "${CURRENT_SCRIPT_DIR}/check-for-broken-symlinks.sh"