docs: Fix terms and refs.

I fail at Sphinx-style ReST.

src/gallium/docs/source/cso/rasterizer.rst

@@ -108,7 +108,7 @@ scissor
     Whether the scissor test is enabled.
 
 multisample
-    Whether :ref:`MSAA` is enabled.
+    Whether :term:`MSAA` is enabled.
 
 bypass_vs_clip_and_viewport
     Whether the entire TCL pipeline should be bypassed. This implies that

src/gallium/docs/source/distro.rst

@@ -112,7 +112,7 @@ driver-specific state structures for later use.
 Draw
 ^^^^
 
-Draw is a software :ref:`TCL` pipeline for hardware that lacks vertex shaders
+Draw is a software :term:`TCL` pipeline for hardware that lacks vertex shaders
 or other essential parts of pre-rasterization vertex preparation.
 
 Gallivm

src/gallium/docs/source/screen.rst

@@ -6,6 +6,8 @@ A screen is an object representing the context-independent part of a device.
 Useful Flags
 ------------
 
+.. _pipe_texture_usage:
+
 PIPE_TEXTURE_USAGE
 ^^^^^^^^^^^^^^^^^^
 
@@ -53,7 +55,7 @@ is_format_supported
 
 See if a format can be used in a specific manner.
 
-**usage** is a bitmask of ``PIPE_TEXTURE_USAGE`` flags.
+**usage** is a bitmask of :ref:`PIPE_TEXTURE_USAGE` flags.
 
 Returns TRUE if all usages can be satisfied.