Added code style

CODE_STYLE.md

@@ -0,0 +1,108 @@
+# Code Style
+
+This document is only meant to teach you the code style used in this project and will not explain *why* this coding style is used.
+
+## Tabs vs Spaces
+
+Use **tabs to indent** and **spaces for alignment** only:
+
+```go
+type AnimeTitle struct {
+	Romaji    string
+	English   string
+	Japanese  string
+	Canonical string
+	Synonyms  []string
+}
+```
+
+## Add an empty line between blocks and other statements
+
+Bad:
+
+```go
+func() {
+	if true {
+		// Block 1
+	}
+	if true {
+		// Block 2
+	}
+	doSomething()
+	doSomething()
+	if true {
+		// Block 3
+	}
+}
+```
+
+Good:
+
+```go
+func() {
+	if true {
+		// Block 1
+	}
+
+	if true {
+		// Block 2
+	}
+
+	doSomething()
+	doSomething()
+
+	if true {
+		// Block 3
+	}
+}
+```
+
+## Variable names
+
+Variables are written in `camelCase` and should clearly state what they contain, preferably with no abbreviations. Common short names like `id` and `url` are allowed.
+
+Iterator variables in loops are an exception to this rule and can be 1-letter, non-significant variable names, usually `i` and `j`.
+
+## Early returns
+
+Do not wrap a whole function in 1 if-block to check parameters. Use early returns.
+
+Bad:
+
+```go
+func DoSomething(a string, b string) {
+	if a != "" && b != "" {
+		doIt(a, b)
+	}
+}
+```
+
+Good:
+
+```go
+func DoSomething(a string, b string) {
+	if a == "" || b == "" {
+		return
+	}
+
+	doIt(a, b)
+}
+```
+
+## Private fields at the end
+
+This is not an absolute rule but try to keep private fields at the end of a struct.
+
+```go
+type MyType struct {
+	PublicA string
+	PublicB string
+	PublicC string
+
+	privateA int
+}
+```
+
+## Package names
+
+Package names should be short lowercase identifiers and tests should be written using the black box pattern. Black box testing can be enabled by adding the suffix `_test` to the package names in `*_test.go` files. It will enable you to test your library like it would be used by another developer, without internal access to private variables.