Provide ability to force a capture method via configuration. (#1063)

Co-authored-by: KuleRucket <luke.d.tucker@gmail.com>

docs/source/about/advanced_usage.rst

@@ -752,6 +752,40 @@ hevc_mode
 
       hevc_mode = 2
 
+capture
+^^^^^^^
+
+**Description**
+   Force specific screen capture method.
+
+   .. Caution:: Applies to Linux only.
+
+**Choices**
+
+.. table::
+   :widths: auto
+
+   =========  ===========
+   Value      Description
+   =========  ===========
+   nvfbc      Use NVIDIA Frame Buffer Capture to capture direct to GPU memory. This is usually the fastest method for
+              NVIDIA cards. For GeForce cards it will only work with drivers patched with
+              `nvidia-patch <https://github.com/keylase/nvidia-patch/>`_
+              or `nvlax <https://github.com/keylase/nvidia-patch/>`_.
+   wlr        Capture for wlroots based Wayland compositors via DMA-BUF.
+   kms        DRM/KMS screen capture from the kernel. This requires that sunshine has cap_sys_admin capability.
+              See :ref:`Linux Setup <about/usage:setup>`.
+   x11        Uses XCB. This is the slowest and most CPU intensive so should be avoided if possible.
+   =========  ===========
+   
+**Default**
+   Automatic. Sunshine will use the first capture method available in the order of the table above.
+
+**Example**
+   .. code-block:: text
+
+      capture = kms
+      
 encoder
 ^^^^^^^