CP-961 Fix formatting of README, update CHANGELOG

[evanweible-wf]

Issue

• The readme has several formatting errors when rendered on pub.dartlang.org (Fix readme formatting on pub #48)
• The changelog is missing the updates that have been merged since 1.0.0

Changes

• Updated README for better rendering on pub.dartlang.org (resolves Fix readme formatting on pub #48)
• Added missing info to CHANGELOG

Displaying the "rich diff" for these files will be helpful since I changed the line length throughout the README and I switched to HTML tables from GitHub's simpler table syntax.

Areas of Regression

n/a

Testing

n/a - we can't really determine how this will look on pub.dartlang.org until it's published there.

Code Review

@trentgrover-wf
@maxwellpeterson-wf
@dustinlessard-wf
@jayudey-wf

[codecov-io]

Current coverage is 48.05%

Merging #70 into master will not affect coverage as of 426a77a

Powered by Codecov. Updated on successful CI builds.

[maxwellpeterson-wf]

+1

[evanweible-wf]

TODO

• Update changelog once CP-960 Widen dart_style range to include ^0.1.8 #69 is merged (doing it here to avoid merge conflict)

[evanweible-wf]

@trentgrover-wf @maxwellpeterson-wf @dustinlessard-wf rebased on latest master, added the change from #69 to the changelog.

[trentgrover-wf]

+1
@jayudey-wf docs only change

[maxwellpeterson-wf]

+1

[dustinlessard-wf]

+1

[jayudey-wf]

QA +1 doc change only

Merging into master