Docs: Fixes and improvements in API documentation

Fixes several notable mistakes and missing information
regarding the API documentation (*.rst).

This will allow API stub generators like bpystubgen or
fake-bpy-module to produce more accurate result.

Differential Revision: https://developer.blender.org/D12639

source/blender/python/gpu/gpu_py_texture.c

@@ -536,7 +536,7 @@ PyDoc_STRVAR(pygpu_texture_from_image_doc,
              "premultiplied or straight alpha matching the image alpha mode.\n"
              "\n"
              "   :arg image: The Image datablock.\n"
-             "   :type image: `bpy.types.Image`\n"
+             "   :type image: :class:`bpy.types.Image`\n"
              "   :return: The GPUTexture used by the image.\n"
              "   :rtype: :class:`gpu.types.GPUTexture`\n");
 static PyObject *pygpu_texture_from_image(PyObject *UNUSED(self), PyObject *arg)