Add docstrings to mkit's functions

mkit/include/common.sh

 }
 
 build1() {
+    #
+    # Process one skeleton
+    #
     local srcpath dstpath
     srcpath=$1
     dstpath=${srcpath%.skel}
 }
 
 build() {
+    #
+    # Add meat to all skeletons
+    #
     local srcpath
     find -type f -name '*.skel' \
      | while read srcpath;
 }
 
 die() {
+    #
+    # Exit with message and non-zero exit status
+    #
     echo "$@" >&2
     exit 4
 }
 }
 
 expand_groups() {
+    #
+    # Read path groups from paths.ini and expand to install params
+    #
     local group
     local mode
     cat "mkit/paths.ini" \
 }
 
 expand_paths() {
+    #
+    # For each path of group $1, print all install params
+    #
     local group=$1
     local mode=$2
     local root="$(get_root $group)"
 }
 
 get_root() {
+    #
+    # Find out target rooot for group $1
+    #
     local group="$1"
     local varname="${group^^*}_DIR"
     test -n "${!varname}" || die "missing in config.mk: $varname"
 }
 
 read_section() {
+    #
+    # Read one INI section
+    #
     local wnt=$1
     local ok=false
     grep '.' \