Remove repeated words

There were two cases of wrong repeated words: `to to` and `not not`,
This removes those and adds a check to `script/test-prose` to prevent
similar repetition from being added in the future.

index.md

@@ -7,4 +7,4 @@ Welcome to the Open Source Handbook! We created this handbook to help creators l
 
 We wrote this handbook based on what we've learned from watching millions of open source projects on GitHub's platform. Whether you're an individual, a company, or a community, you'll find plenty of real stories and experiences in this handbook to guide you.
 
-Special thanks to **(list names of people here)** for their valuable input in the initial release of this handbook. If you'd like to contribute, head on over to to get started!
+Special thanks to **(list names of people here)** for their valuable input in the initial release of this handbook. If you'd like to contribute, head on over to get started!

marketing/measuring.md

@@ -30,7 +30,7 @@ You may also want to track discoverability in specific places: for example, Goog
 
 People are finding your project on this wild and crazy thing we call the internet. Ideally, when they see your project, they'll feel compelled to do something. The second question you'll want to ask is: _are people using my project?_
 
-If you use a package manager, such as npm or RubyGems.org, to distribute your project, you may be able to track your project's downloads. Each package manager may use a slightly different definition of "download", and downloads do not not necessarily correlate to installs or use, but it provides some baseline for comparison.
+If you use a package manager, such as npm or RubyGems.org, to distribute your project, you may be able to track your project's downloads. Each package manager may use a slightly different definition of "download", and downloads do not necessarily correlate to installs or use, but it provides some baseline for comparison.
 
 If your project is on GitHub, navigate again to the "Traffic" page. You can use the [clone graph](https://github.com/blog/1873-clone-graphs) to see how many times your project has been cloned on a given day, broken down by total clones and unique cloners.
 

package.json

@@ -18,6 +18,7 @@
     "retext-equality": "^2.3.2",
     "retext-quotes": "^1.0.0",
     "retext-readability": "^2.0.0",
+    "retext-repeated-words": "^1.0.0",
     "retext-sentence-spacing": "^1.0.0",
     "retext-simplify": "^2.0.0",
     "to-vfile": "^1.0.0",

script/test-prose

@@ -11,6 +11,7 @@ var stringify = require('remark-stringify');
 var english = require('retext-english');
 var sentenceSpacing = require('retext-sentence-spacing');
 var quotes = require('retext-quotes');
+var repeated = require('retext-repeated-words');
 
 // Util stuff
 var report = require('vfile-reporter');
@@ -70,6 +71,7 @@ async.map(ignore.filter(glob.sync("**/*.md")), function(file, callback) {
         .use(english)
         .use(sentenceSpacing, {preferred: 1})
         .use(quotes, {preferred: 'straight'})
+        .use(repeated)
         // .use(require('retext-simplify'), options["simplify"])
         // .use(require('retext-equality'))
         // .use(require('retext-readability'), options["readability"])