[gtk/ebassi/gidocgen: 44/500] docs: Move gdkcairo section to an external file

[Emmanuele Bassi <ebassi src gnome org>]

commit b9f0cf1c8baca7921c61c7f724310c1f33d60813
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Feb 17 14:21:46 2021 +0000

    docs: Move gdkcairo section to an external file

 docs/reference/gdk/cairo.md     | 18 ++++++++++++++++++
 docs/reference/gdk/gdk4.toml.in |  3 +++
 gdk/gdkcairo.c                  | 16 ----------------
 3 files changed, 21 insertions(+), 16 deletions(-)
---
diff --git a/docs/reference/gdk/cairo.md b/docs/reference/gdk/cairo.md
new file mode 100644
index 0000000000..f7d3c969b4
--- /dev/null
+++ b/docs/reference/gdk/cairo.md
@@ -0,0 +1,18 @@
+----
+Title: Cairo interaction
+----
+
+## Functions to support using cairo
+
+[Cairo](http://cairographics.org) is a graphics library that supports vector
+graphics and image compositing that can be used with GTK.
+
+GDK does not wrap the Cairo API; instead it allows to create Cairo
+drawing contexts which can be used to draw on [class@Gdk.Surface]s.
+
+Additional functions allow use [struct@Gdk.Rectangle]s with Cairo
+and to use [struct Gdk RGBA], `GdkPixbuf`, and [class@Gdk.Surface]
+instances as sources for drawing operations.
+
+For more information on Cairo, please see the
+[Cairo API reference](https://www.cairographics.org/manual/).
diff --git a/docs/reference/gdk/gdk4.toml.in b/docs/reference/gdk/gdk4.toml.in
index d64dc616ec..aa343b0a22 100644
--- a/docs/reference/gdk/gdk4.toml.in
+++ b/docs/reference/gdk/gdk4.toml.in
@@ -31,6 +31,9 @@ name = "basic"
 base_url = "https://gitlab.gnome.org/GNOME/gtk/-/blob/master/";
 
 [extra]
+content_files = [
+  "cairo.md",
+]
 content_images = [
   "images/gtk-logo.svg",
   "images/rotated-text.png",
diff --git a/gdk/gdkcairo.c b/gdk/gdkcairo.c
index d28b7e5b97..e36d08fefb 100644
--- a/gdk/gdkcairo.c
+++ b/gdk/gdkcairo.c
@@ -23,22 +23,6 @@
 
 #include <math.h>
 
-/**
- * SECTION:cairo_interaction
- * @Short_description: Functions to support using cairo
- * @Title: Cairo Interaction
- *
- * [Cairo](http://cairographics.org) is a graphics
- * library that supports vector graphics and image compositing that
- * can be used with GDK and GTK.
- *
- * GDK does not wrap the cairo API, instead it allows to create cairo
- * contexts which can be used to draw on #GdkSurfaces. Additional
- * functions allow use #GdkRectangles with cairo and to use #GdkRGBAs,
- * #GdkPixbufs and #GdkSurfaces as sources for drawing operations.
- */
-
-
 /**
  * gdk_cairo_set_source_rgba:
  * @cr: a cairo context