[Fix #699] Changed interactive doc functions to give prompt.

cider-doc, cider-grimoire, jump-to-var and other functions using
cider-read-symbol-name were not interactive without a prefix or
missing symbol.  cider-read-symbol-name now prompts with the
symbol at point as a default.

CHANGELOG.md

@@ -42,6 +42,8 @@
 * [#953](https://github.com/clojure-emacs/cider/pull/953) Use `sshx` instead of `ssh` in `cider-select-endpoint`
 * [#956](https://github.com/clojure-emacs/cider/pull/956) Eval full ns form only when needed.
 * Enable annotated completion candidates by default.
+* [#1031] (https://github.com/clojure-emacs/cider/pull/1031) Interactive functions prompt with
+  symbol at point as a default value.
 
 ### Bugs fixed