3. code-blocks fix

Author: Quattro8

docs/topics/channels.md

@@ -225,7 +225,7 @@ fun CoroutineScope.filter(numbers: ReceiveChannel<Int>, prime: Int) = produce<In
 Now we build our pipeline by starting a stream of numbers from 2, taking a prime number from the current channel, 
 and launching new pipeline stage for each prime number found:
 
-```Plain Text
+```
 numbersFrom(2) -> filter(2) -> filter(3) -> filter(5) -> filter(7) ... 
 ```
 

docs/topics/coroutines-basics.md

@@ -59,7 +59,7 @@ the code with coroutines inside of `runBlocking { ... }` curly braces. This is h
 If you remove or forget `runBlocking` in this code, you'll get an error on the [launch] call, since `launch`
 is declared only on the [CoroutineScope]:
 
-```Plain Text
+```
 Unresolved reference: launch
 ```