async+perf: appendix-B, tweaking wording
async+perf: more tweaks to appendix-B
fixed typo
Merge pull request #240 from hartca/master

fixed typo
async+perf: ch3, clarifying some of the 'spread/unwrap' examples, per #231
async+perf: ch3 and ch4, replacing 'TODO' references with appendix A or B, per #231
async+perf: ch3, tweaking wording per #231