Add basic usage examples

[jidanni]

Please add basic usage examples:

• Junior buys his first bitcoins, with a credit card
• Junior pays XYZ corporation some bitcoins for some service
• Mom sends Junior some bitcoins
• Junior backs up his bitcoins etc. with tar(1) or cpio(1) etc. and puts it on an SD card under his pillow.

[jidanni]

Or add a link to e.g., https://bitzuma.com/posts/a-beginners-guide-to-the-electrum-bitcoin-wallet/