Confusing wording for patch "id" properties

According to the spec, the `"id"` properties for the `add-public-keys` and `add-services` patches are "Base64url encoded", but are not actually being encoded at all. Probably what was meant was to restrict the allowed characters to be the ones from the URL-safe "Base64url" character set i.e. lower case, upper case, digits, `_` and `-`.

https://github.com/decentralized-identity/sidetree/blame/master/docs/spec/patches.md#L40
```
1. The object ****MUST**** include an `id` property, and its value ****MUST**** be a string with no more than fifty (50) Base64URL encoded characters. If the value is not of the correct type or exceeds the specified maximum length, the entire _Patch Action_ ****MUST**** be discarded, without any of the patch being used to modify the DID's state.
```

https://github.com/decentralized-identity/sidetree/blame/master/docs/spec/patches.md#L143
```
1. The object ****MUST**** include an `id` property, and its value ****MUST**** be a string with a length of no more than fifty (50) Base64URL encoded characters. If the value is not of the correct type or exceeds the specified length, the entire _Patch Action_ ****MUST**** be discarded, without any of it being used to modify the DID's state.
```

(Additionally, the two specs for the two `id` properties are very similar, differing only by `a length of` in the first sentence. This could also be made to match for both occurrences.)