Re-word docs for GLFW_OPENGL_DEBUG_CONTEXT attrib

Related to #1720.

docs/window.dox

@@ -1339,8 +1339,8 @@ __GLFW_OPENGL_FORWARD_COMPAT__ is `GLFW_TRUE` if the window's context is an
 OpenGL forward-compatible one, or `GLFW_FALSE` otherwise.
 
 @anchor GLFW_OPENGL_DEBUG_CONTEXT_attrib
-__GLFW_OPENGL_DEBUG_CONTEXT__ is `GLFW_TRUE` if the window's context is an
+__GLFW_OPENGL_DEBUG_CONTEXT__ is `GLFW_TRUE` if the window's context is in debug
-OpenGL debug context, or `GLFW_FALSE` otherwise.
+mode, or `GLFW_FALSE` otherwise.
 
 @anchor GLFW_OPENGL_PROFILE_attrib
 __GLFW_OPENGL_PROFILE__ indicates the OpenGL profile used by the context.  This

include/GLFW/glfw3.h

@@ -1012,9 +1012,9 @@ extern "C" {
  *  and [attribute](@ref GLFW_OPENGL_FORWARD_COMPAT_attrib).
  */
 #define GLFW_OPENGL_FORWARD_COMPAT  0x00022006
-/*! @brief OpenGL debug context hint and attribute.
+/*! @brief Debug mode context hint and attribute.
  *
- *  OpenGL debug context [hint](@ref GLFW_OPENGL_DEBUG_CONTEXT_hint) and
+ *  Debug mode context [hint](@ref GLFW_OPENGL_DEBUG_CONTEXT_hint) and
  *  [attribute](@ref GLFW_OPENGL_DEBUG_CONTEXT_attrib).
  */
 #define GLFW_OPENGL_DEBUG_CONTEXT   0x00022007