docs: fixed docs location and included precool diagram in LayerPlanBuffer (CURA-1932)

Doxyfile

@@ -832,7 +832,7 @@ EXAMPLE_RECURSIVE      = NO
 # that contain images that are to be included in the documentation (see the
 # \image command).
 
-IMAGE_PATH             = documentation/assets
+IMAGE_PATH             = docs/assets
 
 # The INPUT_FILTER tag can be used to specify a program that doxygen should
 # invoke to filter for each input file. Doxygen will invoke the filter program

documentation/Link_to_index.html

@@ -1 +0,0 @@
-html/index.html

src/LayerPlanBuffer.h

@@ -16,6 +16,19 @@
 namespace cura 
 {
 
+/*!
+ * Class for buffering multiple layer plans (\ref GCodePlanner) / extruder plans within those layer plans, so that temperature commands can be inserted in earlier layer plans.
+ * 
+ * This class handles where to insert temperature commands for:
+ * - initial layer temperature
+ * - flow dependent temperature
+ * - starting to heat up from the standby temperature
+ * - initial printing temperature | printing temperature | final printing temperature
+ * 
+ * \image html assets/precool.png "Temperature Regulation" width=10cm
+ * \image latex assets/precool.png "Temperature Regulation" width=10cm
+ * 
+ */
 class LayerPlanBuffer : SettingsMessenger
 {
     GCodeExport& gcode;