Simplify capability encoding diagrams

[arichardson]

Showing all the bounds components the capability encoding overview diagram immediately exposes readers to a lot of complexity that only needs to be understood when implementing the encoding/decoding. Grouping everything together as a BOUNDS field and having the bounds decoding section describe how this is interpreted would push some of that complexity to a more appropriate subsection.
I think the suggestions from @Timmmm in #23 (comment) makes a lot of sense:

---

The other thing that I think would make things clearer is a separate diagram for E=0, but that can probably wait, or maybe go in a separate explanatory document.

[bytefield]
----
(def svg-attrs {:style "background-color:white"})
(defattrs :plain [:plain {:font-family "M+ 1p Fallback" :font-size 30}])
(defattrs :bg-yellow {:fill "#ffffc0"})
(def row-height 80)
(def row-header-fn nil)
(def left-margin 30)
(def right-margin 30)
(def bottom-margin 30)
(def boxes-per-row 32)
(draw-column-headers {:height 50 :font-size 26 :labels [
    "63" "" "" "57"
    "56" "53"
    "52" "48"
    "47" "" "" "" "" "" "" "" "28"
    "27"
    "26" "" "" "" "" "" "" "" "" "" "" "" "" "0"
]})

(draw-box "Reserved"    {:span 4})
(draw-box "SDP"         {:span 2})
(draw-box "AP"          {:span 2})
(draw-box "Reserved"    {:span 9})
(draw-box "S"           {:span 1})
(draw-box "BOUNDS"      [{:span 14} :bg-yellow])
(draw-box "Address"     {:span 32})
----

[bytefield]
----
(def svg-attrs {:style "background-color:white"})
(defattrs :plain [:plain {:font-family "M+ 1p Fallback" :font-size 30}])
(defattrs :bg-yellow {:fill "#ffffc0"})
(def row-height 80)
(def left-margin 30)
(def right-margin 30)
(def bottom-margin 30)
(def boxes-per-row 14)
(draw-column-headers {:height 50 :font-size 26 :labels [
    "26"
    "25" "" "" "17"
    "16" "14"
    "13" "" "" "" "3"
    "2" "0"
]})

(draw-box "EF"          [{:span 1} :bg-yellow])
(draw-box "T[11:3]"     [{:span 4} :bg-yellow])
(draw-box "TE"          [{:span 2} :bg-yellow])
(draw-box "B[13:3]"     [{:span 5} :bg-yellow])
(draw-box "BE"          [{:span 2} :bg-yellow])
----