Touchups to Mix and OTP chapter 7

Notable changes are consistency in naming for "umbrella projects" and
"umbrella children", as discussed in #elixir-lang.
Merge pull request #297 from ernie/otp-chapter-7-touchups

Touchups to Mix and OTP chapter 7
Createad in OTP docs ch 4
Removed extra character
Merge pull request #298 from tallakt/fix_typos

Fix typos
Mix and OTP chapter 8 touchup work
Merge pull request #300 from ernie/otp-chapter-8-touchups

Mix and OTP chapter 8 touchup work
Replace tab with space
Merge pull request #301 from niku/patch-1

Replace tab with space
Touchups to chapter 9

The only non-typo/grammar change to note is that we were referring to
String.split/2 but using String.split/1.
Merge pull request #302 from ernie/otp-chapter-9-touchups

Touchups to chapter 9
Update 8.markdown

I believe the variable should be client as mentioned in L41 to be consistent?
Merge pull request #303 from Ortuna/patch-1

Update 8.markdown
Touchups to Mix and OTP Chapter 10

Of particular note is some exposition on why we might wish to dispatch
router requests to another node vs just run the requested process on the
found node.
Take into account both of José's notes
Merge pull request #304 from ernie/otp-chapter-10-touchups

Touchups to Mix and OTP Chapter 10
Talk about iex.bat on Windows
Rename releases.csv as elixir.csv, create erlang.csv
Merge pull request #305 from chyndman/elixir-erlang-csv

Rename releases.csv as elixir.csv, create erlang.csv
Add introducing Elixir