[pango/line-breaker] lines: Add docs

[Matthias Clasen <matthiasc src gnome org>]

commit 8efa7b3c21c24cdd037370e1a4e1d51e1f92f73d
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jan 24 14:42:37 2022 -0500

    lines: Add docs

 pango/pango-lines.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
---
diff --git a/pango/pango-lines.c b/pango/pango-lines.c
index bf28f9e9..d0f95e57 100644
--- a/pango/pango-lines.c
+++ b/pango/pango-lines.c
@@ -5,6 +5,30 @@
 #include "pango-item-private.h"
 #include "pango-layout-iter-private.h"
 
+/**
+ * PangoLines:
+ *
+ * A `PangoLines` object represents the result of formatting an
+ * entire paragraph (or more) of text.
+ *
+ * A `PangoLines` object contains a list of `PangoLine` objects,
+ * together with information about where to position each line
+ * in layout coordinates.
+ *
+ * `PangoLines` has APIs to query collective information about
+ * its lines (such as ellipsization or unknown glyphs), to translate
+ * between logical character positions within the text and the physical
+ * position of the resulting glyphs, and to determine cursor positions
+ * for editing the text.
+ *
+ * One way to obtain a `PangoLines` object is to use a [class@Pango.Layout].
+ * But it is also possible to populate a `PangoLines` manually with lines
+ * produced by a [class@Pango.LineBreaker] object.
+ *
+ * The most convenient way to access the visual extents and components
+ * of a `PangoLines` is via a [class@Pango.LayoutIter] iterator.
+ */
+
 /*  {{{ PangoLines implementation */
 
 typedef struct _Line Line;