feat: add effect cleanups, add docs (#2)

* docs: update readme

* feat: add cleanup function to effects

* refactor: move peek function to store module

* test: add nested atom check

* docs: add doc comments

* fix: `effect()` type

* refactor: remove divider comment

src/__tests__/effect.spec.luau

@@ -24,7 +24,23 @@ return function()
 
 		unsubscribe()
 		a(4)
-
 		expect(current).to.equal(6)
 	end)
+
+	it("accepts a cleanup function", function()
+		local a = atom(0)
+		local cleanups = 0
+		local unsubscribe = effect(function()
+			a()
+			return function()
+				cleanups += 1
+			end
+		end)
+
+		expect(cleanups).to.equal(0)
+		a(1)
+		expect(cleanups).to.equal(1)
+		unsubscribe()
+		expect(cleanups).to.equal(2)
+	end)
 end

src/__tests__/peek.spec.luau

@@ -1,12 +1,11 @@
 local atom = require(script.Parent.Parent.atom)
-local peek = require(script.Parent.Parent.peek)
 local store = require(script.Parent.Parent.store)
 
 return function()
 	it("calls an atom without capturing it", function()
 		local a, b, c = atom(1), atom(1), atom(1)
 		local captured, result = store.capture(function()
-			return a() + peek(b) + c()
+			return a() + store.peek(b) + c()
 		end)
 		expect(captured[a]).to.be.ok()
 		expect(captured[b]).to.never.be.ok()
@@ -15,8 +14,8 @@ return function()
 	end)
 
 	it("passes through arguments", function()
-		expect(peek(1)).to.equal(1)
-		expect(peek(function()
+		expect(store.peek(1)).to.equal(1)
+		expect(store.peek(function()
 			return 1
 		end)).to.equal(1)
 	end)

src/__tests__/sync/validate.spec.luau

@@ -1,3 +1,4 @@
+local atom = require(script.Parent.Parent.Parent.atom)
 local validate = require(script.Parent.Parent.Parent.sync.validate)
 
 return function()
@@ -13,6 +14,8 @@ return function()
 			number = { value = 1, expected = true },
 			number_infinity = { value = math.huge, expected = false },
 			number_nan = { value = 0 / 0, expected = false },
+
+			nested_atom = { value = atom(0), expected = false },
 		}
 
 		for key, case in cases do