docs: Improve code snippets in release notes

docs/markdown/Release-notes-for-0.43.0.md

@@ -26,7 +26,8 @@ object can be used as a source file for other Targets, this will create a
 dependency on the original `CustomTarget`, but will only insert the generated
 file corresponding to the index value of the `CustomTarget`'s `output` keyword.
 
-    c = CustomTarget(
+```meson
+c = custom_target(
   ...
   output : ['out.h', 'out.c'],
 )
@@ -40,6 +41,7 @@ file corresponding to the index value of the `CustomTarget`'s `output` keyword.
   c[1],
   link_with : lib1,
 )
+```
 
 # Can override executables in the cross file
 
@@ -47,21 +49,26 @@ The cross file can now be used for overriding the result of
 `find_program`. As an example if you want to find the `objdump`
 command and have the following definition in your cross file:
 
+```ini
 [binaries]
 ...
 objdump = '/usr/bin/arm-linux-gnueabihf-objdump-6'
+```
 
 Then issuing the command `find_program('objdump')` will return the
 version specified in the cross file. If you need the build machine's
 objdump, you can specify the `native` keyword like this:
 
+```meson
 native_objdump = find_program('objdump', native : true)
+```
 
 # Easier handling of supported compiler arguments
 
 A common pattern for handling multiple desired compiler arguments, was to
 test their presence and add them to an array one-by-one, e.g.:
 
+```meson
 warning_flags_maybe = [
   '-Wsomething',
   '-Wanother-thing',
@@ -74,12 +81,15 @@ test their presence and add them to an array one-by-one, e.g.:
   endif
 endforeach
 cc.add_project_argument(warning_flags)
+```
 
 A helper has been added for the foreach/has_argument pattern, so you can
 now simply do:
 
+```meson
 warning_flags = [ ... ]
 flags = cc.get_supported_flags(warning_flags)
+```
 
 # Better support for shared libraries in non-system paths
 
@@ -93,12 +103,14 @@ This means that e.g. supporting prebuilt libraries shipped with your
 source or provided by subprojects or wrap definitions by writing a
 build file like this:
 
+```meson
 project('myprebuiltlibrary', 'c')
 
 cc = meson.get_compiler('c')
 prebuilt = cc.find_library('mylib', dirs : meson.current_source_dir())
 mydep = declare_dependency(include_directories : include_directories('.'),
                            dependencies : prebuilt)
+```
 
 Then you can use the dependency object in the same way as any other.