message: clean up footnotes for GitHub
diff: @@ -86,7 +86,7 @@ the `float` creator function, which should be found in the
  the `OSP_REGISTER_SG_NODE_NAME` macro, described more in detail in [Creating
  Your Own Node Type](#creating-your-own-node-type).
  -A node's `value` is an `Any` type [^anytype].
  +A node's `value` is an `Any` type[^1].
  ### Node Properties
  @@ -117,7 +117,7 @@ they play in the SG.
  A node's connections to its parent and children are also held in `properties`.
  Children are held in a `FlatMap`, with keys being child node names and values
  -being pointers to the child nodes [^flatmaptype].
  +being pointers to the child nodes[^2].
  Finally, a number of `TimeStamp` objects track the modification status of this
  node and its children. These are used to determine if a subtree of the SG needs
  @@ -272,7 +272,7 @@ The `OSPNode` type is for nodes encapsulating OSPRay objects, such as a
  `Camera`, `World`, or a `Light`. Many of the classes defined throughout the
  `sg/` directory define these types of nodes. They hold a C++ wrapped object
  (using the OSPRay C++ API) within a `handle()`. Any children of these nodes are
  -automatically provided to this internal object as an OSPRay parameter[^sgonly].
  +automatically provided to this internal object as an OSPRay parameter[^3].
  Child nodes use their name to select the OSPRay parameter name, and their value
  as the parameter's value.
  @@ -335,13 +335,13 @@ for `RGBNode`s, and so on.
  ---
  -[^anytype]: The `Any` type comes from `rkcommon`, in `utility/Any.h`. It
  +[^1]: The `Any` type comes from `rkcommon`, in `utility/Any.h`. It
  provides a C++11 interface similar to C++17's `std::any`.
  -[^flatmaptype]: The `FlatMap` type comes from `rkcommon`, in
  +[^2]: The `FlatMap` type comes from `rkcommon`, in
  `utility/FlatMap.h`. It provides a similar interface to `std::map`, but uses
  an `std::vector` for faster lookups.
  -[^sgonly]: Nodes may be marked as `sgOnly` to prevent this. For example,
  +[^3]: Nodes may be marked as `sgOnly` to prevent this. For example,
  `Geometry` nodes have a boolean visibility toggle that is not a valid OSPRay
  `Geometry` parameter.
  