docs: extend usage examples

Author: antongolub

README.md

@@ -3,37 +3,53 @@
 
 ## Install
 ```sh
-yarn add envapi
+npm install envapi
 ``` 
 
 ## Usage
 ```ts
 import { parse, stringify, config, load, loadSafe } from 'envapi'
 
-const str = `
+const input = `A=A\nFOO=BAR`
+const env = parse(input) // { A: 'A', FOO: 'BAR' }
+const output = stringify(env) // A=A\nFOO=BAR
+```
+
+### parse()
+Parse a dotenv string into an object.
+
+```ts
+const raw = `
 A=A
-FOO = """bar
-baz
-"""
-X:x #comment`
-
-const env = parse(str)
-{
-  A: 'A',
-  FOO: 'bar\nbaz',
-  X: 'x'
-}
-
-const nstr = stringify(env)
-`A=A
-FOO="bar\nbaz"
-X=x`
-
-const raw = 'FOO=BAR\nBAZ=QUX'
-await fs.writeFile('.env', raw)
-const env1 = load('.env')
-
-config('.env')
+FOO=BAR #comment`
+
+const env = parse(raw) // { A: 'A', FOO: 'BAR' }
+```
+
+### stringify()
+Stringify an object into a dotenv string.
+    
+```ts
+const env = { A: 'A', FOO: 'BAR' }
+const raw = stringify(env) // 'A=A\nFOO=BAR'
+```
+
+### load()
+Read a dotenv file(s) and parse it into an object. `loadSafe()` suppresses ENOENT errors.
+```ts
+await fs.writeFile('.env1', 'FOO=BAR')
+await fs.writeFile('.env2', 'BAZ=QUX')
+
+const env = load('.env1', '.env2')      // { FOO: 'BAR', BAZ: 'QUX' }
+const _env = loadSafe('.env.notexists') // {}
+```
+
+
+### config()
+Load a dotenv file into `process.env`.
+
+```ts
+config('.env1')
 process.env.FOO // BAR
 ```