Release 0.6.2

[taiki-e]

Changes:

• Update serde-xml-rs to 0.5 (#26)
• Performance improvement (#18)

This PR also includes the following (see the first, second, and third commits for more):

• Use docs.rs badge instead of doc link (369d43ad45488400da741d5cb446999e80ffc58a)
• Replace manually maintained contributor list with contributors image by contrib.rocks (369d43ad45488400da741d5cb446999e80ffc58a) [rendered]
• Use readme as crate-level docs (369d43ad45488400da741d5cb446999e80ffc58a)
• Update license text to match original (b4445320234bcd80107bec3ce1401d5e8abbac4d)
• Fix compile error in example in readme (27fff2186f26659cad81f6c9a60cde2e5f1ee79f)