Fix some spaces/tabs/0 width spaces in the proof mode docs.

ProofMode.md

@@ -137,13 +137,13 @@ You can write
 
 which results in:
 
-				x : nat
-				H : x = 0
-				______________________________________(1/1)
-				​​"HQ" : Q
-				​"HR" : R
-				--------------------------------------□
-				R ★ Q ∧ x = 1
+        x : nat
+        H : x = 0
+        ______________________________________(1/1)
+				"HQ" : Q
+        "HR" : R
+        --------------------------------------□
+        R ★ Q ∧ x = 1
 
 
 Specialization patterns