updates the documentation to follow the list-style to explain arguments.

As per to @jon-turney's and @jpakanne's suggestion [0], this commit
changes the "prosa" documentation to a list-style one.

[0] https://github.com/mesonbuild/meson/pull/2529#pullrequestreview-72265697

docs/markdown/Qt5-module.md

@@ -5,10 +5,13 @@ tools and steps required for Qt. The module has one method.
 
 ## preprocess
 
-This method takes six keyword arguments, `moc_headers`, `moc_sources`, `ui_files`, `qresources`
-and `moc_extra_arguments` which define the files that require preprocessing with `moc`, `uic`
-and `rcc` and 'include_directories' which might be needed by moc as well as (optional)
-additional arguments. It returns an opaque object that should be passed to a main build target.
+This method takes the following keyword arguments:
+ - `moc_headers`, `moc_sources`, `ui_files`, `qresources`, which define the files that require preprocessing with `moc`, `uic` and `rcc`
+ - `include_directories`, the directories to add to header search path for `moc` (optional)
+ - `moc_extra_arguments`, any additional arguments to `moc` (optional).
+
+It returns an opaque object that should be passed to a main build target.
+
 A simple example would look like this:
 
 ```meson