Fix quaternion typos.

PiperOrigin-RevId: 453203844
Change-Id: I7d788c21bb00b7746f941fb2cf755f0b046e35f2

doc/XMLreference.rst

@@ -2783,7 +2783,7 @@ subelements. The file format starts with a header of 4 integers: nvertex, ntexco
 the same as in meshes, and specify the total number of vertices, texture coordinate pairs, and triangle faces in the
 skin. ntexcoord can be zero or equal to nvertex. nbone specifies the number of MuJoCo bodies that will be used as
 bones in the skin. The header is followed by the vertex, texcoord and face data, followed by a specification for each
-bone. The bone specification contains the name of the corresponding model body, 3D bind position, 4D bind quaterion,
+bone. The bone specification contains the name of the corresponding model body, 3D bind position, 4D bind quaternion,
 number of vertices influenced by the bone, and the vertex index array and weight array. Body names are represented as
 fixed-length character arrays and are expected to be 0-terminated. Characters after the first 0 are ignored. The
 contents of the SKN file are:
@@ -5020,7 +5020,7 @@ bodies whose center of mass is of interest.
 :at:`objname`: :at-val:`string, required`
    Name of the MuJoCo object to which the sensor is attached.
 :at:`datatype`: :at-val:`[real, positive, axis, quaternion], required`
-   The type of output generated by this sensor. "axis" means a unit-length 3D vector. "quat" means a unit quaterion.
+   The type of output generated by this sensor. "axis" means a unit-length 3D vector. "quat" means a unit quaternion.
    These need to be declared because when MuJoCo adds noise, it must respect the vector normalization. "real" means a
    generic array (or scalar) of real values to which noise can be added independently.
 :at:`needstage`: :at-val:`[pos, vel, acc], required`