Documentation: vgaarbiter: Fix grammar

Correct grammar issues:

- Fix "co-exist" subject-verb agreement
- Correct plural form of "server" in context of more than one legacy
  devices
- Use passive mood for intro sentence of libpciaccess section

Signed-off-by: Pranav Tyagi <pranav.tyagi03@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20250220164946.18007-1-pranav.tyagi03@gmail.com
[Bagas: massage commit message]
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250318041249.20786-2-bagasdotme@gmail.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>

Documentation/gpu/vgaarbiter.rst

@@ -11,9 +11,9 @@ Section 7, Legacy Devices.
 
 The Resource Access Control (RAC) module inside the X server [0] existed for
 the legacy VGA arbitration task (besides other bus management tasks) when more
-than one legacy device co-exists on the same machine. But the problem happens
+than one legacy device co-exist on the same machine. But the problem happens
 when these devices are trying to be accessed by different userspace clients
-(e.g. two server in parallel). Their address assignments conflict. Moreover,
+(e.g. two servers in parallel). Their address assignments conflict. Moreover,
 ideally, being a userspace application, it is not the role of the X server to
 control bus resources. Therefore an arbitration scheme outside of the X server
 is needed to control the sharing of these resources. This document introduces
@@ -106,7 +106,7 @@ In-kernel interface
 libpciaccess
 ------------
 
-To use the vga arbiter char device it was implemented an API inside the
+To use the vga arbiter char device, an API was implemented inside the
 libpciaccess library. One field was added to struct pci_device (each device
 on the system)::