Corrected a typo in a function's signature and modified the documentation to...

Corrected a typo in a function's signature and modified the documentation to reflect the code better.

examples/test_bh_new.c

@@ -416,14 +416,15 @@ static inline int are_neighbours(struct cell *ci, struct cell *cj) {
 
 /**
  * @brief Interacts all count particles in parts
- * with the monopole in cj
+ * with a series of multipoles
  *
- * @param parts An array of particles
+ * @param parts An array of local particles
  * @param count The number of particles in the array
- * @param cj The cell with which the particles will interact
+ * @param mults The multipoles to interact with
+ * @param mult_count The number of multipoles to interact with
  */
 static inline void make_interact_pc(struct part_local *parts, int part_count, 
-				    struct multipole_local mults[7], int mult_count) {
+				    struct multipole_local mults[8], int mult_count) {
 
   int i, j, k;
   float dx[3] = {0.0, 0.0, 0.0}, r2, ir, w;