docs: move specs to a separate folder

Handle legacy/obsolete specs as well
List all specs in extensions.html
Mark 'OLD' extensions as obsolete in extensions.html
Update the spec location in old relnotes

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Brian Paul <brianp@vmware.com>

docs/specs/MESA_release_buffers.spec

@@ -0,0 +1,85 @@
+Name
+
+    MESA_release_buffers
+
+Name Strings
+
+    GLX_MESA_release_buffers
+
+Contact
+
+    Brian Paul (brian.paul 'at' tungstengraphics.com)
+
+Status
+
+    Shipping since Mesa 2.0 in October, 1996.
+
+Version
+
+    Last Modified Date:  8 June 2000
+
+Number
+
+    217
+
+Dependencies
+
+    OpenGL 1.0 or later is required.
+    GLX 1.0 or later is required.
+
+Overview
+
+    Mesa's implementation of GLX is entirely implemented on the client side.
+    Therefore, Mesa cannot immediately detect when an X window or pixmap is
+    destroyed in order to free any ancillary data associated with the window
+    or pixmap.
+
+    The glxMesaReleaseBuffers() function can be used to explicitly indicate
+    when the back color buffer, depth buffer, stencil buffer, and/or accumu-
+    lation buffer associated with a drawable can be freed.
+
+IP Status
+
+    Open-source; freely implementable.
+
+Issues
+
+    None.
+
+New Procedures and Functions
+
+    Bool glXReleaseBuffersMESA( Display *dpy, GLXDrawable d );
+
+New Tokens
+
+    None.
+
+Additions to Chapter 3 of the GLX 1.3 Specification (Functions and Errors)
+
+    The function
+
+	Bool glXReleaseBuffersMESA( Display *dpy, GLXDrawable d );
+
+    causes all software ancillary buffers (back buffer, depth, stencil,
+    accum, etc) associated with the named drawable to be immediately
+    deallocated.  True is returned if <d> is a valid Mesa GLX drawable,
+    else False is returned.  After calling glXReleaseBuffersMESA, the
+    drawable should no longer be used for GL rendering.  Results of
+    attempting to do so are undefined.
+
+
+GLX Protocol
+
+    None, since this is a client-side operation.
+
+Errors
+
+    None.
+
+New State
+
+    None.
+
+Revision History
+
+    8 June 2000 - initial specification