update primitive docs

Author: ngokevin

docs/primitives/a-box.md

@@ -23,7 +23,7 @@ The box primitive, formerly called `<a-cube>`, creates shapes such as boxes, cub
 
 ## Attributes
 
-Note that the box primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the box primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute | Component Mapping | Default Value |
 |-----------|-------------------|---------------|

docs/primitives/a-circle.md

@@ -0,0 +1,35 @@
+---
+title: <a-circle>
+type: primitives
+layout: docs
+parent_section: primitives
+---
+
+Flat circle.
+
+## Example
+
+```html
+<a-scene>
+  <a-assets>
+    <img id="texture" src="texture.jpg">
+  </a-assets>
+
+  <!-- Basic circle. -->
+  <a-circle color="#CCC" radius="2"></a-circle>
+
+  <!-- Textured circle parallel to ground. -->
+  <a-circle src="#texture" rotation="-90 0 0"></a-circle>
+</a-scene>
+```
+
+## Attributes
+
+Note that the circle primitive inherits [common attributes](./common-attributes.md).
+
+| Attribute    | Component Mapping    | Default Value |
+|--------------|----------------------|---------------|
+| radius       | geometry.radius      | 1             |
+| segments     | geometry.segments    | 32            |
+| theta-length | geometry.thetaLength | 360           |
+| theta-start  | geometry.thetaStart  | 0             |

docs/primitives/a-collada-model.md

@@ -27,7 +27,7 @@ The COLLADA model primitive displays a 3D COLLADA model created from a 3D modeli
 
 ## Attribute
 
-Note that the COLLADA model primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the COLLADA model primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute | Component Mapping | Default Value |
 |-----------|-------------------|---------------|

docs/primitives/a-cone.md

@@ -23,7 +23,7 @@ The cone primitive creates a cone shape. It is an entity that prescribes the [ge
 
 ## Attributes
 
-Note that the cone primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the cone primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute       | Component Mapping       | Default Value |
 |-----------------|-------------------------|---------------|

docs/primitives/a-curvedimage.md

@@ -27,7 +27,7 @@ The curved image primitive creates images that bend around the user. Curved imag
 
 ## Attributes
 
-Note that the curved image primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the curved image primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute       | Component Mapping       | Default Value   |
 |-----------------|-------------------------|-----------------|

docs/primitives/a-cylinder.md

@@ -27,7 +27,7 @@ The cylinder primitive is versatile and can actually be used to create various s
 
 ## Attributes
 
-Note that the cylinder primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the cylinder primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute       | Component Mapping       | Default Value |
 |-----------------|-------------------------|---------------|

docs/primitives/a-image.md

@@ -25,7 +25,7 @@ The image primitive displays an image on a flat plane. It is an entity that pres
 
 ## Attributes
 
-Note that the image primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the image primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute | Component Mapping | Default Value |
 |-----------|-------------------|---------------|

docs/primitives/a-plane.md

@@ -25,7 +25,7 @@ The plane primitive creates flat surfaces. It is an entity that prescribes the [
 
 ## Attributes
 
-Note that the plane primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the plane primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute | Component Mapping | Default Value |
 |-----------|-------------------|---------------|

docs/primitives/a-ring.md

@@ -23,7 +23,7 @@ The ring primitive creates a ring or disc shape. It is an entity that prescribes
 
 ## Attributes
 
-Note that the ring primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the ring primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute      | Component Mapping      |
 |----------------|------------------------|

docs/primitives/a-sky.md

@@ -23,7 +23,7 @@ A plain color as a background:
 
 ## Attributes
 
-Note that the sky primitive inherits common [mesh attributes](./mesh-attributes.md).
+Note that the sky primitive inherits [common attributes](./common-attributes.md).
 
 | Attribute       | Component Mapping       | Default Value |
 |-----------------|-------------------------|---------------|