Minor checkdoc fixes

Minor checkdoc fixes

* eglot.el (eglot, eglot--when-buffer-window, eglot--widening)
(eglot-initialization-options, eglot--current-flymake-report-fn)
(eglot-handle-notification, eglot-handle-request)
(eglot--highlight-piggyback, eglot-register-capability)
(eglot-unregister-capability):
* eglot-tests.el (auto-detect-running-server, auto-shutdown)
(auto-reconnect, eglot--tests-force-full-eldoc, rename-a-symbol)
(basic-completions, non-unique-completions, basic-xref)
(snippet-completions, snippet-completions-with-company)
(eglot-eldoc-after-completions, python-yapf-formatting)
(javascript-basic, json-basic, eglot-ensure)
(eglot--guessing-contact): Doc fixes; formatting.

* eglot.el (xref-backend-identifier-completion-table): Fix error
format.