Merge rust-bitcoin/rust-bitcoin#970: Fix badges

a0a83e1 README: Use correct license (Tobin C. Harding)
5c363bc README: Update badge to Rust 1.41.1 (Tobin C. Harding)

Pull request description:

  We have two small bugs in our README badges

  - Patch 1: sets the MSRV badge to the new 1.41.1
  - Patch 2: sets the license badge to the correct license, CC0

  (To verify that the changes render correctly, click on the 'from' branch name above.)

ACKs for top commit:
  sanket1729:
    ACK a0a83e1
  apoelstra:
    ACK a0a83e1

Tree-SHA512: e216cd36ac3ea477146c1a8ac842718dfe07762dd47378b7862a6ad5f92a08c25ed92133543fdc083d5edd80d08e7da46e1f87067c14d3240b3e411b2a05baf3

Author: apoelstra

README.md

@@ -9,10 +9,10 @@
 
   <p>
     <a href="https://crates.io/crates/bitcoin"><img alt="Crate Info" src="https://img.shields.io/crates/v/bitcoin.svg"/></a>
-    <a href="https://github.com/rust-bitcoin/rust-bitcoin/blob/master/LICENSE"><img alt="MIT or Apache-2.0 Licensed" src="https://img.shields.io/badge/license-MIT%2FApache--2.0-blue.svg"/></a>
+    <a href="https://github.com/rust-bitcoin/rust-bitcoin/blob/master/LICENSE"><img alt="CC0 1.0 Universal Licensed" src="https://img.shields.io/badge/license-CC0--1.0-blue.svg"/></a>
     <a href="https://github.com/rust-bitcoin/rust-bitcoin/actions?query=workflow%3AContinuous%20integration"><img alt="CI Status" src="https://github.com/rust-bitcoin/rust-bitcoin/workflows/Continuous%20integration/badge.svg"></a>
     <a href="https://docs.rs/bitcoin"><img alt="API Docs" src="https://img.shields.io/badge/docs.rs-bitcoin-green"/></a>
-    <a href="https://blog.rust-lang.org/2018/09/13/Rust-1.29.html"><img alt="Rustc Version 1.29+" src="https://img.shields.io/badge/rustc-1.29%2B-lightgrey.svg"/></a>
+    <a href="https://blog.rust-lang.org/2020/02/27/Rust-1.41.1.html"><img alt="Rustc Version 1.41.1+" src="https://img.shields.io/badge/rustc-1.41.1%2B-lightgrey.svg"/></a>
     <a href="https://gnusha.org/bitcoin-rust/"><img alt="Chat on IRC" src="https://img.shields.io/badge/irc-%23bitcoin--rust%20on%20libera.chat-blue"></a>
     <img alt="Lines of code" src="https://img.shields.io/tokei/lines/github/rust-bitcoin/rust-bitcoin">
   </p>