adds explanation of the InnerSource spelling

Author: spier

meta/README.md

@@ -11,3 +11,5 @@ The topics below cover information about how we define, operate, and upkeep this
 * [Contributing](../CONTRIBUTING.md) - How to interact with our group, create your own patterns, or take part in our review-process; Github / Web centric instructions
   * [Alternate Command-line steps](./technical-git-howto.md) - If you want to contribute a pattern using `git` from the command-line, this is your document
   * [Meetings](./meetings.md) - Become involved with the people and communications of the Inner Source Patterns group
+* **(incomplete) Writing Guidelines** - To make the writing for our patterns more consistent, we provide some guidelines to help the various authors to keep a consistent voice.
+  * [InnerSource Spelling](./innersource-spelling.md) - Clarifies the mystery around how to spell this. Spoiler: It is **InnerSource**.

meta/innersource-spelling.md

@@ -0,0 +1,42 @@
+# InnerSource Spelling
+
+We recommend the spelling **InnerSource**.
+
+We encourage you to use the word as a proper noun (like “We use InnerSource in that repo”) wherever possible. We discourage the use of verb forms of the word (like “We’re inner-sourcing that repo”).
+
+## Full story - Why we care about the spelling
+
+**InnerSource** is an artificial term that does necessarily have a spelling that would naturally be correct. Therefore you will find various spellings when you search for the term online.
+
+We favor the spelling **InnerSource**, for the following reasons:
+
+1. That’s the way Tim O’Reilly [spelled it in 2000][opengl_1200] (he was into Perl and camel-case was a thing).
+2. If you set up side-by-side Google searches for “Inner Source” and “InnerSource” you will find that you get more hits on the former term, by only 1% of them have anything to do with what we call InnerSource. The latter term will be 100% cogent to your inquiry.
+3. The OSI was [denied trademark on the term “open source”][no-open-source-trademark] because it was made up of two common and unrelated terms. “InnerSource” on the other hand is a new word.
+
+## But the spelling isn't even consistent in the InnerSource Patterns repo!
+
+You are right, it isn't consistent. Not yet! But we are getting there. :)
+
+The reason you see multiple spellings in our documentation is that it was built over a period of years during which our thinking on the spelling crystallized.
+
+For new patterns we stick to the spelling **InnerSource**. Old patterns will be reworked over time to use this spelling as well.
+
+## It can be hard to use the term "InnerSource" in a sentence
+
+Some people have had a hard time with the camel-case term **InnerSource** because they’re not sure how to use it in a sentence grammatically.
+
+We recommend not to turn the term into a verb, but rather using it as a noun our adjective.
+
+Recommended use:
+
+“We use InnerSource in that repo”
+or
+“We use InnerSource methods in that repo”
+
+Not so good:
+
+“We’re InnerSourcing that repo”
+
+[opengl_1200]: https://web.archive.org/web/20180411080939/http://archive.oreilly.com/pub/a/oreilly/ask_tim/2000/opengl_1200.html
+[no-open-source-trademark]: https://opensource.org/pressreleases/certified-open-source.php