Weird characters: add names

[daveliepmann]

This PR adds names for the weird symbols (e.g. "tilde" for "~") on the Reading Clojure Characters page.

The "weird characters"/"Reading Clojure Characters" page's goal is to improve findability. Adding English names for these special characters makes it easier to search within a page as well as to use search engines (which can make it difficult to search with special characters). Referring to these characters by name is also helpful for Clojure users who aren't familiar with them, for instance when English is not their native language.

I tried to add as little verbiage as possible.

• [x] Have you read the guidelines for contributing?
• [x] Have you signed the Clojure Contributor Agreement? [yes, 05/25/2017]
• [x] Have you verified your asciidoc markup is correct?

Note: I did not change any asciidoc markup, however due to jblake issues on M1 I was not able to preview the changes locally.