Update Permissions.md (#1529)

Size comes first on fieldsh

heapster-saw/doc/Permissions.md

@@ -72,7 +72,7 @@ In addition to the above expressions, we also have shape expressions, which we s
 | `sh1 ; sh2`                 | `llvmshape w` | A sequence of two shapes |
 | `[l]ptrsh(rw,sh)`           | `llvmshape w` | A shape for a pointer to another memory block, i.e. a memblock permission, with a given shape. This memblock permission will have the same read/write and lifetime modalities as the memblock permission containing this pointer shape, unless they are specifically overridden by the pointer shape; i.e., we have that `[l]memblock(rw,off,len,[l']ptrsh(rw',sh)) = [l]memblock(rw,off,len, fieldsh([l']memblock(rw',0,len(sh),sh)))`, where `rw'` and/or `l'` can be `Nothing`, in which case they default to `rw` and `l`, respectively. |
 | `fieldsh(p)`                | `llvmshape w` | A shape for a single pointer field, given a permission that acts on a pointer of unknown size. |
-| `fieldsh(p,sz)`             | `llvmshape w` | Like `fieldsh(p)`, but where the permission acts on a pointer of size `sz`. |
+| `fieldsh(sz,p)`             | `llvmshape w` | Like `fieldsh(p)`, but where the permission acts on a pointer of size `sz`. |
 | `arraysh(s,len,sh)`         | `llvmshape w` | A shape for an array with the given stride, length (in number of elements = total length / stride), and fields `sh` |
 | `exsh x:a.sh`               | `llvmshape w` | An existential shape |