docs: Consistently capitalise page titles

Signed-off-by: Philip Withnall <pwithnall@gnome.org>

Helps: #3037

docs/reference/glib/character-set.md

@@ -1,8 +1,8 @@
-Title: Character set conversions
+Title: Character Set Conversions
 SPDX-License-Identifier: LGPL-2.1-or-later
 SPDX-FileCopyrightText: 2010, 2012, 2014 Matthias Clasen
 
-# Character set conversions
+# Character Set Conversions
 
 The [`func@GLib.convert`] family of function wraps the functionality of
 iconv(). In addition to pure character set conversions, GLib has functions

docs/reference/glib/goption.md

@@ -1,6 +1,6 @@
-Title: Commandline option parser
+Title: Commandline Option Parser
 
-# Commandline option parser
+# Commandline Option Parser
 
 The GOption commandline parser is intended to be a simpler replacement
 for the popt library. It supports short and long commandline options,

docs/reference/gobject/boxed.md

@@ -1,6 +1,6 @@
-Title: Boxed types
+Title: Boxed Types
 
-# Boxed types
+# Boxed Types
 
 A "boxed type" is a generic wrapper mechanism for arbitrary C structures.
 The only thing the type system needs to know about the structures is how to

docs/reference/gobject/enum-types.md

@@ -1,6 +1,6 @@
-Title: Enumeration types
+Title: Enumeration Types
 
-# Enumeration types
+# Enumeration Types
 
 The GLib type system provides fundamental types for enumeration and flags
 types. Enumerations types are collection of identifiers associated with a

docs/reference/gobject/floating-refs.md

@@ -1,6 +1,6 @@
-Title: Floating references
+Title: Floating References
 
-# Floating references
+# Floating References
 
 **Note**: Floating references are a C convenience API and should not be used
 in modern GObject code. Language bindings in particular find the concept

docs/reference/gobject/gvalue.md

@@ -1,6 +1,6 @@
-Title: Generic value container
+Title: Generic Value Container
 
-# Generic value container
+# Generic Value Container
 
 The [`struct@GObject.Value`] structure is basically a variable container
 that consists of a type identifier and a specific value of that type. The