es5-shim limitation need to be explicitly stated

[allenwb]

A concern:

Since this package is getting a fair amount of twitter and blog visibility, I'm concerned that some false expectations are being created. In particular, it isn't clear from the description of the project that it while it provides an ES5 compatible API but that it does not and cannot provide ES5 semantic extensions that are not already present in the "older" browser.

This shows up in all legacy browsers for functions such as Object.freeze and the inability to set property attributes. For IE<9 browsers it will show up as an inability to define getter/setter properties. User's of this package really should be warned of these limitations.

[kriskowal]

Thanks, Allen. I didn't realize it was getting so much attention, although there have been a fair number of comments today; I haven't even written a README yet. I'll make sure to put up a sign post.

[kriskowal]

Thanks. 554ca0c