Improved documentation for texture completeness.

(Almost) nobody will notice that in function documentation, so it's now
only in class documentation.

src/AbstractTexture.h

@@ -468,9 +468,6 @@ class MAGNUM_EXPORT AbstractTexture {
          *
          * Sets filter used when the object pixel size is smaller than the
          * texture size.
-         * @attention This, @ref Texture::setWrapping() "setWrapping()" and
-         * setMagnificationFilter() must be called after creating the texture,
-         * otherwise the texture will be incomplete.
          * @attention For rectangle textures only some modes are supported,
          * see @ref AbstractTexture::Filter "Filter" and
          * @ref AbstractTexture::Mipmap "Mipmap" documentation for more
@@ -484,9 +481,6 @@ class MAGNUM_EXPORT AbstractTexture {
          *
          * Sets filter used when the object pixel size is larger than largest
          * texture size.
-         * @attention This, @ref Texture::setWrapping() "setWrapping()" and
-         * setMinificationFilter() must be called after creating the texture,
-         * otherwise the texture will be incomplete.
          */
         inline void setMagnificationFilter(Filter filter) {
             bind();

src/Texture.h

@@ -30,7 +30,9 @@ Template class for one- to three-dimensional textures.
 
 @attention Don't forget to call setWrapping(), setMinificationFilter() and
 setMagnificationFilter() after creating the texture, otherwise the texture
-will be incomplete.
+will be incomplete. If you specified mipmap filtering in
+setMinificationFilter(), be sure to also either explicitly set all mip levels
+or call generateMipmap().
 
 The texture is bound via bind() and setting texture uniform on the shader to the
 texture (see AbstractShaderProgram::setUniform(GLint, const AbstractTexture*)).
@@ -113,9 +115,6 @@ template<size_t textureDimensions> class Texture: public AbstractTexture {
          * Sets wrapping type for coordinates out of range (0, 1) for normal
          * textures and (0, textureSizeInGivenDirection-1) for rectangle
          * textures.
-         * @attention This, setMinificationFilter() and
-         * setMagnificationFilter() must be called after creating the texture,
-         * otherwise the texture will be incomplete.
          * @attention For rectangle textures only some modes are supported,
          * see @ref AbstractTexture::Wrapping "Wrapping" documentation for
          * more information.