Remove sole reference to embedded exponent

"Embedded" and "internal" have very similar meanings in English so it's pretty confusing for them to mean opposite things in CHERI. Fortunately there was only one reference to "embedded" so it's easy enough to remove it.

src/cap-description.adoc

@@ -225,7 +225,7 @@ address
 into the capability's address
 * *EF:* Exponent format flag indicating the encoding for T, B and E
     ** The exponent is stored in T and B if EF=0, so it is 'internal'
-    ** The exponent is zero if EF=1, so it is 'embedded'
+    ** The exponent is zero if EF=1
 
 The bit width of T and B are defined in terms of the mantissa width (MW) which
 is set depending on the value of XLENMAX as shown in