[pango/bilelmoussaoui/gi-annotations] Flesh out some doc comments

[Matthias Clasen <matthiasc src gnome org>]

commit 46fc53896c67eaca25da0876ea7ee8160410fdd8
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Oct 29 08:05:07 2021 -0400

    Flesh out some doc comments
    
    Add some missing details about new enumerations
    and run baselines.

 pango/pango-attributes.h |  9 +++++++--
 pango/pango-layout.c     | 10 +++++++++-
 2 files changed, 16 insertions(+), 3 deletions(-)
---
diff --git a/pango/pango-attributes.h b/pango/pango-attributes.h
index 982987f8..51b9b077 100644
--- a/pango/pango-attributes.h
+++ b/pango/pango-attributes.h
@@ -232,6 +232,7 @@ typedef enum {
 
 /**
  * PangoBaselineShift:
+ * @PANGO_BASELINE_SHIFT_NONE: Leave the baseline unchanged
  * @PANGO_BASELINE_SHIFT_SUPERSCRIPT: Shift the baseline to the superscript position,
  *   relative to the previous run
  * @PANGO_BASELINE_SHIFT_SUBSCRIPT: Shift the baseline to the subscript position,
@@ -249,8 +250,12 @@ typedef enum {
 
 /**
  * PangoFontScale:
- * @PANGO_FONT_SCALE_SUPERSCRIPT: 
- * @PANGO_FONT_SCALE_SUBSCRIPT: 
+ * @PANGO_FONT_SCALE_NONE: Leave the font size unchanged
+ * @PANGO_FONT_SCALE_SUPERSCRIPT: Change the font to a size suitable for superscripts
+ * @PANGO_FONT_SCALE_SUBSCRIPT: Change the font to a size suitable for subscripts
+ *
+ * An enumeration that affects font sizes for superscript
+ * and subscript positioning.
  *
  * Since: 1.50
  */
diff --git a/pango/pango-layout.c b/pango/pango-layout.c
index f91b91d3..ba81adf6 100644
--- a/pango/pango-layout.c
+++ b/pango/pango-layout.c
@@ -7510,9 +7510,17 @@ pango_layout_iter_get_baseline (PangoLayoutIter *iter)
 }
 
 /**
- * pango_layout_iter_get_run_baseline
+ * pango_layout_iter_get_run_baseline:
  * @iter: a `PangoLayoutIter`
  * 
+ * Gets the Y position of the current run's baseline, in layout
+ * coordinates.
+ *
+ * Layout coordinates have the origin at the top left of the entire layout.
+ *
+ * The run baseline can be different from the line baseline, for
+ * example due to superscript or subscript positioning.
+ *
  * Since: 1.50
  */
 int