Some edits of typos in the "SMIs and Doubles"

[melikhov-dev]

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[melikhov-dev]

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-    this.add('rcx', 8);
+    this.add('rcx', tag);

I see this.stub('rax', 'Alloc', 8, 1); below. Why tag size is 1 byte? Maybe this.stub('rax', 'Alloc', 8, 8);?

[indutny]

I think tag size is supposed to be 8 bytes... Although it is a bit hard for me to fully recollect what's going on there.