adding: instructions to memory management subjects

subjects/arrange_it/README.md

@@ -5,7 +5,7 @@
 Create a **function** called `arrange_phrase` that takes a string literal as a phrase and returns it organized
 Each word will have a number that indicates the position of that word.
 
-> This exercise will test the **heap allocation** of your function!
+> This exercise will test how many times the **heap is going to be allocated**!\
 > So try your best to allocate the minimum data on the heap!
 
 ### Expected Function

subjects/name_initials/README.md

@@ -5,7 +5,7 @@
 Create a **function** called `initials`, this function will receive a vector of string literals
 with names and return a vector of Strings with the initials of each name.
 
-> This exercise will test the **heap allocation** of your function!
+> This exercise will test how many times the **heap is going to be allocated**!\
 > So try your best to allocate the minimum data on the heap!
 
 ### Notions
@@ -15,7 +15,7 @@ with names and return a vector of Strings with the initials of each name.
 ### Expected Function
 
 ```rust
-pub fn initials(names: &mut Vec<&str>) -> Vec<String> {
+pub fn initials(names: Vec<&str>) -> Vec<String> {
 }
 ```
 
@@ -27,8 +27,8 @@ Here is a program to test your function:
 use name_initials::initials;
 
 fn main() {
-    let mut names = vec!["Harry Potter", "Someone Else", "J. L.", "Barack Obama"]
-    println!("{:?}", initials(&mut names));
+    let names = vec!["Harry Potter", "Someone Else", "J. L.", "Barack Obama"]
+    println!("{:?}", initials(names));
 }
 ```
 

subjects/string_literals/README.md

@@ -10,8 +10,8 @@ Create the following functions:
 - `split_at`, that divides a string in two returning a tuple
 - `find', that returns the index if the first character of a given string that matches the pattern
 
-> This exercise will test the **heap allocation** of your function!
-> So try your best to allocate the minimum data on the heap! (hit: &str)
+> This exercise will test how many times the **heap is going to be allocated**!\
+> So try your best to allocate the minimum data on the heap!
 
 ### Notions