Update 01.md

Small grammatical change for easier reading

01.md

@@ -43,7 +43,7 @@ To obtain the `event.id`, we `sha256` the serialized event. The serialization is
 ```
 
 To prevent implementation differences from creating a different event ID for the same event, the following rules MUST be followed while serializing:
-- No whitespace, line breaks or other unnecessary formatting should be included in the output JSON.
+- Whitespace, line breaks or other unnecessary formatting should not be included in the output JSON.
 - No characters except the following should be escaped, and instead should be included verbatim:
   - A line break, `0x0A`, as `\n`
   - A double quote, `0x22`, as `\"`