Updated WIP Manual: Loading roms (markdown)

WIP-Manual:-Loading-roms.md

@@ -3,6 +3,7 @@
 >
 > The information on this page is accurate to **release 2.9.1** and will not reflect more recent changes.
 > It also may not be accurate to older versions.
+> Unless specified, all functions are available on every supported OS.
 
 EmuHawk supports [many formats](#TODO) of cart and disc images ('roms').
 For most of these, simply **dragging and dropping the file onto the main EmuHawk window will load it**.
@@ -10,6 +11,12 @@ Alternatively, you can launch a file picker with `File` ⟩ `Open ROM...`:
 
 ![screencap with menu item highlighted](https://gitlab.com/TASVideos/BizHawk/uploads/d8ea751d1d01a619f4f374d61a548fc7/open_rom.png)
 
+Alternatively, in most desktop environments (including Windows and KDE Plasma),
+roms can be 'associated' with the EmuHawk application by using your file manager's "Open With..." option.
+Doing this allows roms to be opened in EmuHawk by double-clicking them.
+If single-instance mode is enabled and EmuHawk is already open,
+opening a rom file that's associated with EmuHawk will cause the rom to open in the existing instance.
+
 A few of the supported formats use multiple files.
 - For `.bin`+`.cue`, load the `.cue`.
 	The `.bin` file must be in the location listed in the `.cue`, which is typically a relative path to a sibling file i.e. `.\<filename>.bin`.
@@ -34,7 +41,7 @@ Set your core preferences under `Config`&nbsp;⟩ `Preferred Cores`:
 
 ![screencap with menu item highlighted](https://gitlab.com/TASVideos/BizHawk/uploads/b21e6281f4fd17d8f058bacc9c3d2dca/core_preference_neshawk.png)
 
-> Note: Playing back movies temporarily overrides your core preference.
+> Note: Playing back movies **temporarily overrides your core preference**.
 > [This guide on resyncing](#TODO) explains how to use a different core for a movie.
 
 ## Automation
@@ -44,7 +51,8 @@ On the command-line, if the last argument isn't part of a flag pair, it's interp
 > Note: If on **Linux** and using the provided launch script, paths must be **relative to the install dir** or absolute.
 > You can use `$PWD` or `$(pwd)` to get an absolute path for the current dir.
 
-If single-instance mode is enabled, launching a new EmuHawk instance with a rom filepath specified will cause it to open in the existing instance.
+If single-instance mode is enabled and EmuHawk is already open,
+launching EmuHawk with a rom filepath specified will cause the rom to open in the existing instance.
 
 Roms can be loaded via ApiHawk with the `IEmuClientApi.OpenRom` method.
 It takes 1 argument: the filepath as a `string`.