Fix docs calling GLFW_CONTEXT_REVISION a hint

This docstring previously indicated that GLFW_CONTEXT_REVISION was
a window hint and attribute, but in fact it is only a window attribute
(there is no code which uses this constant in any other context.)

We noticed this in https://github.com/hexops/mach/pull/71/files#r749741814

Closes #1992

Signed-off-by: Stephen Gutekanst <[email protected]>
(cherry picked from commit 37fc28bff6cad7164aa67e828e9317596f8080da)

include/GLFW/glfw3.h

@@ -960,7 +960,7 @@ extern "C" {
  *  and [attribute](@ref GLFW_CONTEXT_VERSION_MINOR_attrib).
  */
 #define GLFW_CONTEXT_VERSION_MINOR  0x00022003
-/*! @brief Context client API revision number hint and attribute.
+/*! @brief Context client API revision number attribute.
  *
  *  Context client API revision number
  *  [attribute](@ref GLFW_CONTEXT_REVISION_attrib).