Update Geargrafx docs

Author: drhelius

docs/library/geargrafx.md

@@ -5,13 +5,13 @@
 Geargrafx is an open source, cross-platform, PC Engine / TurboGrafx-16 / SuperGrafx emulator written in C++.
 
 - Accurate emulation supporting the entire HuCard PCE / SGX catalog
-- CD-ROM² and Super CD-ROM² systems
+- CD-ROM², Super CD-ROM² and Arcade CD-ROM² systems
 - Multi Tap support (up to 5 players)
 - Controllers:
     * Standard Gamepad (2 buttons)
     * Avenue Pad 3 (3 buttons, auto-configured based on game)
     * Avenue Pad 6 (6 buttons)
-- Internal database for automatic rom detection
+- Internal database for automatic rom detection and hardware selection if `Auto` options are selected
 - Backup RAM support
 - Save state support
 - Retro Achievements support
@@ -54,9 +54,10 @@ Content that can be loaded by the Geargrafx core have the following file extensi
 
 - .pce
 - .sgx
-- .bin
-- .rom
 - .cue
+- .chd
+
+Geargrafx supports `chd`, `cue/bin`, `cue/img` and `cue/iso` CD-ROM images. `cue/iso + wav` is also supported when audio track format is 44100Hz, 16 bit, stereo. It does not support MP3 or OGG audio tracks.
 
 RetroArch database(s) that are associated with the Geargrafx core:
 
@@ -186,6 +187,10 @@ Settings with (restart) means that core has to be closed for the new setting to
 
     Specify the BIOS file to use for CD-ROM emulation. The *Auto* setting automatically selects the appropriate BIOS based on the loaded content. You can also manually choose one for compatibility with specific games.
 
+- **Preload CD-ROM (restart)** [geargrafx_cdrom_preload] (**Disabled**|Enabled)
+
+    This option will preload all CD-ROM tracks in RAM. It will increase the memory usage of the core, but may improve performance.
+
 - **No Sprite Limit** [geargrafx_no_sprite_limit] (**Disabled**|Enabled)
 
     Enabling this option removes the per-line sprite limit, but may cause glitches in certain games.
@@ -207,6 +212,21 @@ Settings with (restart) means that core has to be closed for the new setting to
     This may cause movement based glitches to occur in certain games.
     It's best to keep this core option disabled.
 
+- **PSG Volume** [geargrafx_psg_volume] (**100**|0 - 200)
+
+    This option sets the volume of the PSG sound system, which is used for sound effects and music in many games.
+    The value is a percentage from 0 to 200, where 100 is the default volume.
+
+- **CD-ROM Volume** [geargrafx_cdrom_volume] (**100**|0 - 200)
+
+    This option sets the volume of the CD-ROM sound system, which is used for music in CD-ROM games.
+    The value is a percentage from 0 to 200, where 100 is the default volume.
+
+- **ADPCM Volume** [geargrafx_adpcm_volume] (**100**|0 - 200)
+
+    This option sets the volume of the ADPCM sound system, which is typically used for speech in CD-ROM games.
+    The value is a percentage from 0 to 200, where 100 is the default volume.
+
 ## Joypad
 
 | RetroPad Inputs                             | PCE Pad (2-button) | Avenue Pad 3 (3-button)    | Avenue Pad 6 (6-button) |