Version management documentation

[NickNaso]

There is a little inconsistency on Napi::VersionManagement documentation.

Now the two static methods exposed by Napi::VersionManagement are documented like reported below:

static uint32_t GetNapiVersion(Env env);

static const napi_node_version* GetNodeVersion(Env env);

instead they will be fixed as reported below:

static uint32_t Napi::VersionManagement::GetNapiVersion(Env env);

static const napi_node_version* Napi::VersionManagement::GetNodeVersion(Env env);

[nadongguri]

Hi @NickNaso, I will take this issue.

[NickNaso]

I'm closing this issue because it has been solved with #360