Add entry to changelog, remove TODO

Author: RJ722

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 * Add a "Give Feedback" button (#551, Rahul Jha).
 * Test code on macOS (#552, Rahul Jha).
+* Support searching for multiple words (#558, Rahul Jha).
 
 # 2.21 (2020-12-07)
 * Update MathJax to version 3 (#515, @dgcampea).

TODO.md

@@ -14,7 +14,6 @@ please check back with me briefly about its status.
 - [ ] Check that non-ASCII image filenames work (https://bugs.launchpad.net/bugs/1739701).
 - [ ] Search and replace (useful for renaming tags and other names).
       Show "replace" text field after search text has been entered.
-- [ ] Add simple way to show all entries: allow searching for whitespace (i.e., don't strip whitespace from search string).
 - [ ] Copy files and pictures into data subdirectory (#163, #469).
 - [ ] Require minimum width for calendar panel to avoid hiding it by accident.