[doc] catch up the CHANGES.txt file for recent changes

CHANGES.txt

@@ -5,11 +5,23 @@ Version 0.4.0 (in progress)
 -----------------------------
 
 * Require Octave 7.x or later.
+* Fix Octave 7.x and 8.x compatibility in installation and package loading.
+* Fix `string.missing()` and to actually return a missing value, instead of "".
 * Remove `(fill,rm,standardize)missing` functions, deferring to the Statistics package.
+* Fix `table` "preallocation" constructor to use 0s and ""s for fill values, unless missings are requested using an alternate pseudotype. (For compatibility with Matlab.)
 * Fix `x(ix) = []` element deletion for string, datetime, table, and other classes.
+* Add idempotent one-arg constructor forms for string, datetime, categorical. (But not table.)
 * Add `istable` function.
+* Add `NaS` and `NaC` functions.
 * Rename `+tablicious` package to `+tblish`; merge `+octave` package into `+tblish`.
 * Move `+table_examples` package to `+tblish/+examples`.
+* Make internal-use properties on the main classes Access = private, now that the code is a little more mature.
+* Fix the doco generation, including publishing to GitHub Pages.
+
+Internal:
+
+* Convert code style to GNU Octave code style, mostly.
+* Move `mustBe*` functions to a `validators/` subdirectory, just for tidiness.
 * Revamp doc-generation tools.
 
 Version 0.3.7 (2023-01-05)
@@ -82,5 +94,5 @@ Version 0.1.0 (2019-04-30)
 
 Initial release!
 
-This library is about 2/3 feature complete. Most basic table, string, categorical, and 
+This library is about 2/3 feature complete. Most basic table, string, categorical, and
 Missing Data stuff is working, and there's documentation.