add semi decision doc

docs/decisions/007-no-semi.md

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+# No Semicolons
+
+Date: 2024-06-14
+
+Status: accepted
+
+## Context
+
+First off, I want to call out that by not using semicolons, we are not relying
+on
+[automatic semicolon insertion](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#automatic_semicolon_insertion).
+We have build tools and things that are going to compile our code and minify it
+and everything, they'll add the semicolons for us automatically.
+
+Another issue people have with leaving off semicolons is you can start a line
+with a bracket or a parentheses and that can cause problems if the previous line
+doesn't have a semicolon. We're not gonna have those problems because we use the
+[`no-unexpected-multiline`](https://eslint.org/docs/latest/rules/no-unexpected-multiline)
+rule from ESLint (not to mention prettier makes the code look funny if you try
+that). For example, if you were to write something like this:
+
+<!-- prettier-ignore -->
+```js
+let firstPerson
+const people = [
+	{ id: 1, name: 'Bob', age: 8 },
+	{ id: 2, name: 'Alice', age: 11 },
+	{ id: 3, name: 'Charlie', age: 15 },
+	{ id: 4, name: 'Dave', age: 7 },
+	{ id: 5, name: 'Eve', age: 13 }
+]
+[firstPerson] = people
+```
+
+Prettier would rewrite it to look like this:
+
+```js
+let firstPerson
+const people = ([
+	{ id: 1, name: 'Bob', age: 8 },
+	{ id: 2, name: 'Alice', age: 11 },
+	{ id: 3, name: 'Charlie', age: 15 },
+	{ id: 4, name: 'Dave', age: 7 },
+	{ id: 5, name: 'Eve', age: 13 },
+][firstPerson] = people)
+```
+
+Which makes it much more obvious something weird is happening. This is just a
+non-issue.
+
+Sure, ok, so the problems aren't really problems. Great. But why turn off
+semicolons? Turning off semicolons makes the process of refactoring our code
+easier by not having to babysit the semicolons. For example:
+
+<!-- prettier-ignore -->
+```js
+const people = [
+	{ id: 1, name: 'Bob', age: 8 },
+	{ id: 2, name: 'Alice', age: 11 },
+	{ id: 3, name: 'Charlie', age: 15 },
+	{ id: 4, name: 'Dave', age: 7 },
+	{ id: 5, name: 'Eve', age: 13 },
+];
+
+const olderThanTenAges = people
+	.map((person) => person.age)
+	.filter((age) => age > 10);
+```
+
+Notice that the final chained operation has a semicolon. If I decided to do the
+filter before the map I have to first remove the semicolon, then move the line.
+I call this "semicolon babysitting". However, if I don't have semicolons then I
+simply move the line.
+
+It's small, but it's also just one less thing to worry about when refactoring
+code and it shows up in enough situations like this one and others that it's
+enough reason to set `semi` to `false`.
+
+## Decision
+
+Set the prettier config to `semi: false`.
+
+## Consequences
+
+This is the way the config was from the beginning so it won't affect existing
+users. Anyone who wants to use this config and wants to use semicolons can
+override that option.