message: Add more f0 sample values
diff: @@ -561,15 +561,20 @@ n_{ior} = \frac{2}{1 - \sqrt{\fNormal}} - 1
  Table [commonMatReflectance] describes acceptable Fresnel reflectance values for various types of materials (no real world material has a value under 2%).
  - Material | Reflectance
  ---------------------------:|:---------------------
  -Glass | 3.5%
  -Water | 2%
  -Common liquids | 2% to 4%
  -Common gemstones | 5% to 16%
  -Other dielectric materials | 2% to 5%
  -Default value | 4%
  -[Table [commonMatReflectance]: Reflectance of common materials]
  + Material | Reflectance | Linear value
  +--------------------------:|:-----------------|:----------------
  +Water | 2% | 0.35
  +Fabric | 4% to 5.6% | 0.5 to 0.59
  +Common liquids | 2% to 4% | 0.35 to 0.5
  +Common gemstones | 5% to 16% | 0.56 to 1.0
  +Plastics, glass | 4% to 5% | 0.5 to 0.56
  +Other dielectric materials | 2% to 5% | 0.35 to 0.56
  +Eyes | 2.5% | 0.39
  +Skin | 2.8% | 0.42
  +Hair | 4.6% | 0.54
  +Teeth | 5.8% | 0.6
  +Default value | 4% | 0.5
  +[Table [commonMatReflectance]: Reflectance of common materials (source: Real Time Rendering 4th Edition)]
  Table [fNormalMetals] lists the $\fNormal$ values for a few metals. The values are given in sRGB and must be used as the base color in our material model. Please refer to the annex, section [Specular color], for an explanation of how these sRGB colors are computed from measured data.
  