Add more Nim examples (#2265)

* Add more Nim examples

* Newlines :P

* Replace it with openArray

* Remove march, seq

* fix typo

CONTRIBUTORS.md

@@ -89,3 +89,4 @@ From oldest to newest contributor, we would like to thank:
 - [Kale Blankenship](https://github.com/vcabbage)
 - [George Gribkov](https://github.com/GeorgeGribkov)
 - [Artem Akatev](https://github.com/aakatev)
+- [Danil Yarantsev](https://github.com/Yardanico)

examples/nim/Max_array.nim

@@ -0,0 +1,5 @@
+# For best results compile with -d:danger
+proc maxArray(x: var seq[float], y: seq[float]) {.exportc.} = 
+  for i in 0 ..< x.len:
+    if y[i] > x[i]:
+      x[i] = y[i]

examples/nim/Sum_over_array.nim

@@ -0,0 +1,4 @@
+# For best results compile with -d:danger
+proc sumArray(data: seq[int]): int {.exportc.} = 
+  for elem in data:
+    result += elem