docs: document Intel, R300 env vars
diff --git a/docs/envvars.html b/docs/envvars.html
index b2c0e01..bb1c914 100644
--- a/docs/envvars.html
+++ b/docs/envvars.html
@@ -51,5 +51,24 @@
</ul>
+<p>
+These environment variables are for the Intel i945/i965 drivers:
+</p>
+<ul>
+<li>INTEL_STRICT_CONFORMANCE - if set to 1, enable sw fallbacks to improve
+ OpenGL conformance. If set to 2, always use software rendering.
+<li>INTEL_NO_BLIT - if set, disable hardware-accelerated glBitmap,
+ glCopyPixels, glDrawPixels.
+</ul>
+
+
+<p>
+These environment variables are for the Radeon R300 driver:
+</p>
+<ul>
+<li>R300_NO_TCL - if set, disable hardware-accelerated Transform/Clip/Lighting.
+</ul>
+
+
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