Clarify env.json docs around arrays that have len elements rather tha…

…n len bytes, fix #749

soroban-env-common/env.json

@@ -917,7 +917,7 @@
                         }
                     ],
                     "return": "MapObject",
-                    "docs": "Return a new map initialized from a set of input slices given by linear-memory addresses and lengths."
+                    "docs": "Return a new map initialized from a pair of equal-length arrays, one for keys and one for values, given by a pair of linear-memory addresses and a length in Vals."
                 },
                 {
                     "export": "c",
@@ -941,7 +941,7 @@
                         }
                     ],
                     "return": "Void",
-                    "docs": "Copy the Val values of a map, as described by set of input keys, into an array at a given linear-memory address."
+                    "docs": "Copy Vals from `map` to the array `vals_pos`, selecting only the keys identified by the array `keys_pos`. Both arrays have `len` elements and are identified by linear-memory addresses."
                 }
             ]
         },
@@ -1223,7 +1223,7 @@
                         }
                     ],
                     "return": "VecObject",
-                    "docs": "Return a new vec initialized from an input slice of Vals given by a linear-memory address and length."
+                    "docs": "Return a new vec initialized from an input slice of Vals given by a linear-memory address and length in Vals."
                 },
                 {
                     "export": "h",
@@ -1243,7 +1243,7 @@
                         }
                     ],
                     "return": "Void",
-                    "docs": "Copy the Vals of a vec into an array at a given linear-memory address."
+                    "docs": "Copy the Vals of a vec into an array at a given linear-memory address and length in Vals."
                 }
             ]
         },