bump mdBook to v0.5.2

Handbook/bin/sg-preprocessor.sh

@@ -33,8 +33,8 @@ fi
 
 readonly JSON_INPUT=$(cat)
 
-readonly CONTEXT=$(echo "${JSON_INPUT}" | xq '.[0]')
-readonly BOOK=$(echo "${JSON_INPUT}" | xq '.[1]')
+readonly CONTEXT=$(printf '%s' "${JSON_INPUT}" | xq '.[0]')
+readonly BOOK=$(printf '%s' "${JSON_INPUT}" | xq '.[1]')
 
 escape_string() {
     printf '%s' "$1" | sed -e 's/\\/\\\\/g' -e 's/"/\\"/g'
@@ -63,8 +63,8 @@ SG_PLUGIN_VERSION_PATCH_ESCAPED=$(escape_string "${SG_PLUGIN_VERSION_PATCH}")
 SG_BUILD_HOST_ESCAPED=$(escape_string "${SG_BUILD_HOST}")
 SG_BUILD_TIME_ESCAPED=$(escape_string "${SG_BUILD_TIME}")
 
-PARSED_BOOK=$(echo "${BOOK}" | xq "
-    .sections[] |= (
+PARSED_BOOK=$(printf '%s' "${BOOK}" | xq "
+    .items[] |= (
         if has(\"Chapter\") then
             .Chapter.content |=
                 walk(if type == \"string\" then
@@ -103,4 +103,4 @@ PARSED_BOOK=$(echo "${BOOK}" | xq "
 #echo "BOOK: ${BOOK}" >&2
 #echo "PARSED_BOOK: ${PARSED_BOOK}" >&2
 
-echo "${PARSED_BOOK}" | xq '.'
+printf '%s' "${PARSED_BOOK}"