fix emojis

docs/lectures/acn/11_connecting.md

@@ -104,9 +104,9 @@ Precedence
 
 **IPv6** supports 128-bit addresses
 
-- Loads of addresses :white_check_mark:
-- Routing protocols need to be ported :negative_squared_cross_mark:
-- Associated services needing to move :negative_squared_cross_mark:
+- Loads of addresses ✅
+- Routing protocols need to be ported ❌
+- Associated services needing to move ❌
 
 ### Network Address Translation
 

docs/lectures/cryptography/01_intro.md

@@ -65,7 +65,7 @@ $a=12, m=7$
 
 $a\equiv 5 (mod\space 7)$
 
-$\frac{7}{12-5}$ :white_check_mark:
+$\frac{7}{12-5}$ ✅
 
 This can be rewritten as: $a = q\cdot m+r$
 

docs/lectures/cryptography/10_RSA.md

@@ -24,14 +24,14 @@
     - $gcd(a,m) = 1$
 - The **Euler totient** $\Phi$ is the number of integers in $\mathbb{Z}_m = \{0,1,...m-1\}$ for which $gcd(a,m)=1$
     - For example $\Phi(9)=6$ as:
-        - $gcd(1,9)=1$ :white_check_mark:
-        - $gcd(2,9)=1$ :white_check_mark:
+        - $gcd(1,9)=1$ ✅
+        - $gcd(2,9)=1$ ✅
         - $gcd(3,9)=3$ ❌
-        - $gcd(4,9)=1$ :white_check_mark:
-        - $gcd(5,9)=1$ :white_check_mark:
+        - $gcd(4,9)=1$ ✅
+        - $gcd(5,9)=1$ ✅
         - $gcd(6,9)=3$ ❌
-        - $gcd(7,9)=1$ :white_check_mark:
-        - $gcd(8,9)=1$ :white_check_mark:
+        - $gcd(7,9)=1$ ✅
+        - $gcd(8,9)=1$ ✅
 
 #### Integer Factorisation