[std.range.iota] Improve in operator docs (#10868)

Author: ntrel

std/algorithm/comparison.d

@@ -82,8 +82,12 @@ Returns:
     found value plus one is returned.
 
 See_Also:
-$(REF_ALTTEXT find, find, std,algorithm,searching) and $(REF_ALTTEXT canFind, canFind, std,algorithm,searching) for finding a value in a
-range.
+    $(UL
+    $(LI $(REF_SHORT find, std,algorithm,searching) and
+    $(REF_SHORT canFind, std,algorithm,searching) for finding a value in a range.)
+    $(LI $(REF_ALTTEXT `value in iota(start, end)`, iota, std,range) to find a value in
+    a particular interval.)
+    )
 */
 uint among(alias pred = (a, b) => a == b, Value, Values...)
     (Value value, Values values)

std/range/package.d

@@ -6847,12 +6847,15 @@ pure @safe nothrow unittest
    user-defined types that support `++`, the range is an input
    range.
 
-   An integral iota also supports `in` operator from the right. It takes
-   the stepping into account, the integral won't be considered
-   contained if it falls between two consecutive values of the range.
-   `contains` does the same as in, but from lefthand side.
+   $(DDOC_SECTION_H `in` operator and `contains`:)
+   `iota` over an integral/pointer type defines the `in` operator from the right.
+   `val in iota(...)` is true when `val` occurs in the range. When present, it takes
+   `step` into account - `val` won't be considered
+   contained if it falls between two consecutive elements of the range.
+   The `contains` method does the same as `in`, but from the left-hand side.
 
     Example:
+    $(RUNNABLE_EXAMPLE
     ---
     void main()
     {
@@ -6879,6 +6882,7 @@ pure @safe nothrow unittest
         writeln();
     }
     ---
+    )
 */
 auto iota(B, E, S)(B begin, E end, S step)
 if ((isIntegral!(CommonType!(B, E)) || isPointer!(CommonType!(B, E)))