[release-notes] Flesh out the developers page more

[Matthias Clasen <matthiasc src gnome org>]

commit 43771db98ce246a53cd49389cf2ffa9b2809e73a
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Mar 22 14:40:38 2021 -0400

    Flesh out the developers page more

 help/C/developers.page | 51 ++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 12 deletions(-)
---
diff --git a/help/C/developers.page b/help/C/developers.page
index b2547241..5fc874cb 100644
--- a/help/C/developers.page
+++ b/help/C/developers.page
@@ -28,16 +28,11 @@
 
   <section id="gtk">
     <title>GTK 4</title>
-    <p>GTK is the toolkit used by GNOME applications. A major new
-    version, GTK 4, has been released towards the end of 2020. Among the many
-    changes in this release are hardware-accelerated rendering, new scalable
-    list widgets, and out-of-the-box support for video.</p>
-  </section>
-
-  <section id="tracker">
-    <title>Tracker</title>
-    <p>Tracker has gained a new batch API, which provides a more efficient
-    way to insert data.</p>
+    <p>GTK is the toolkit used by GNOME applications. A major new version, GTK 4,
+    has been released towards the end of 2020. Among the many changes in this
+    release are hardware-accelerated rendering, new scalable list widgets, and
+    out-of-the-box support for video.</p>
+    <p>To learn more about GTK 4, visit <link href="https://www.gtk.org/";>www.gtk.org</link></p>
   </section>
 
   <section id="libhandy">
@@ -52,12 +47,44 @@
     </list>
   </section>
 
+  <section id="gsv">
+    <title>GtkSourceView</title>
+    <p>GtkSourceView 5 is a port of this library to GTK 4 with a modernized
+    GObject API. Its features include:</p>
+    <list>
+      <item><p>Improved syntax highlighting performance by using
+      the JIT provided in PCRE2</p></item>
+      <item><p>A new autocompletion engine</p></item>
+      <item><p>Support for "Interactive tooltips"</p></item>
+      <item><p>A new code-snippet engine</p></item>
+    </list>
+  </section>
+
+  <section id="sysprof">
+    <title>Sysprof</title>
+    <p><app>Sysprof</app> is a system profiler for GNOME which uses the Linux
+    perf API. In GNOME &gnomeversion;, the symbol decoding of <app>Sysprof</app>
+    has been improved when using containers such as Flatpak or Toolbox.</p>
+  </section>
+
+  <section id="builder">
+    <title>Builder</title>
+    <p><app>Builder</app> is an IDE written for GNOME with good support for
+    many languages, and for Flatpak. In GNOME &gnomeversion;, <app>Builder</app>
+    can now more accurately discover SDK extensions and install them for you.</p>
+    <p><app>Builder</app>'s Rust support will now install and run rust-analyzer
+    from your Flatpak build container to improve diagnostics, completion, and
+    code-formatting features for this language.</p>
+  </section>
+
   <section id="more">
     <title>Other Improvements</title>
     <p>Other improvements in GNOME &gnomeversion; include:</p>
     <list>
-      <item><p><app>Sysprof</app> has learned to decode stack traces from containers</p></item>
-      <item><p>List some gnome-builder things here</p></item>
+      <item><p>The <app>sysprof-cli</app> tool will now pre-authorize the profiling session before spawning 
processes.</p></item>
+      <item><p><app>Builder</app> has better support for Toolbox containers.</p></item>
+      <item><p>Tracker has gained a new batch update API, <link 
href="https://gnome.pages.gitlab.gnome.org/tracker/docs/api-preview/libtracker-sparql-3/TrackerBatch.html";>TrackerBatch</link>,
+    which provides a more efficient way to insert data.</p></item>
     </list>
   </section>