doc: Add fpi-assembling section to the docs

doc/libfprint-docs.xml

@@ -43,6 +43,7 @@
     <xi:include href="xml/fpi-ssm.xml"/>
     <xi:include href="xml/fpi-poll.xml"/>
     <xi:include href="xml/fpi-img.xml"/>
+    <xi:include href="xml/fpi-assembling.xml"/>
     <xi:include href="xml/fpi-usb.xml"/>
   </part>
 

doc/libfprint-sections.txt

@@ -218,6 +218,18 @@ fpi_std_sq_dev
 fpi_mean_sq_diff_norm
 </SECTION>
 
+<SECTION>
+<INCLUDE>fpi-assembling.h</INCLUDE>
+<FILE>fpi-assembling</FILE>
+fpi_frame
+fpi_frame_asmbl_ctx
+fpi_line_asmbl_ctx
+
+fpi_do_movement_estimation
+fpi_assemble_frames
+fpi_assemble_lines
+</SECTION>
+
 <SECTION>
 <INCLUDE>fpi-usb.h</INCLUDE>
 <FILE>fpi-usb</FILE>

libfprint/fpi-assembling.c

@@ -31,6 +31,16 @@
 
 #include "fpi-assembling.h"
 
+/**
+ * SECTION:fpi-assembling
+ * @title: Image frame assembly
+ *
+ * Those are the helpers to manipulate capture data from fingerprint readers
+ * into a uniform image that can be further processed. This is usually used
+ * by drivers for devices which have a small sensor and thus need to capture
+ * data in small stripes.
+ */
+
 static unsigned int calc_error(struct fpi_frame_asmbl_ctx *ctx,
 			       struct fpi_frame *first_frame,
 			       struct fpi_frame *second_frame,