docs: add description

Author: rwv

.github/workflows/build.yml

@@ -55,4 +55,5 @@ jobs:
         run: |
           aws lambda publish-layer-version \
             --layer-name mutool \
-            --content S3Bucket=mutool-layer,S3Key=mutool-layer.zip
+            --content S3Bucket=mutool-layer,S3Key=mutool-layer.zip \
+            --description "MuPDF CLI tools v1.24.10"