Add docstring to local variables

bin/ssl_fp

@@ -9,7 +9,8 @@ usage() {
 }
 
 cached() {
-    local cache_size=$(stat -c %s "$Cache")
+    local cache_size    # size of cache, just to help debugging
+    cache_size=$(stat -c %s "$Cache")
     debug -v Cache cache_size
     if test "$cache_size" -gt 0;
     then
@@ -40,9 +41,9 @@ get_fps() {
 }
 
 main() {
-    local Conn
-    local Cache
-    local es
+    local Conn      # connection target (SERVER:PORT)
+    local Cache     # cert cache (for re-computing hashes)
+    local es        # exit status
     #shellcheck disable=SC2034
     while true; do case "$1" in
         *:*) Conn="$1";             shift ;;