Correct Zcherilevels EL clearing table

When the authorizing EL is zero, we also clear EL on the loaded cap
(if it is tagged).

Fixes: #432

src/level-ext.adoc

@@ -127,8 +127,9 @@ NOTE: if W=0 or C=0 then SL is irrelevant
 |==============================================================================
    4+|Auth cap field             | Data cap field |
     h|*R*   h|*C* h|*EL* h|*CL* h| Tag           h|Action
-.4+.^|1 .4+.^| 1   | 1    | X    | X              |Load data capability unmodified
-              .3+.^| 0    | 1    | X              |Load data capability unmodified
+.5+.^|1 .5+.^| 1   | 1    | X    | X              |Load data capability unmodified
+              .4+.^| 0    | 1    | 1              |Load data capability with EL=0
+                          | 1    | 0              |Load data capability unmodified
                      .2+.^| 0    | 1              |Load data capability with CL=0,EL=0
                                  | 0              |Load data capability unmodified
 |==============================================================================