Update changelog (#459)

* Update changelog

* Update changelog.md

Author: Saransh-cpp

docs/changelog.md

@@ -1,5 +1,29 @@
 # Changelog
 
+## Version 1.4
+
+### Version 1.4.0
+
+#### Features
+
+- feat: allow coord values in to\_<coord_names> methods [#446][]
+- feat: a sympy backend [#442][]
+
+#### Bug fixes
+
+- fix: call the square implementation for power 2 on object vectors [#444][]
+- fix: use negfactor in negfactor scale test [#456][]
+
+#### Maintenance
+
+- chore: test on numpy 2.0 [#451][]
+
+[#446]: https://github.com/scikit-hep/vector/pull/446
+[#442]: https://github.com/scikit-hep/vector/pull/442
+[#444]: https://github.com/scikit-hep/vector/pull/444
+[#456]: https://github.com/scikit-hep/vector/pull/456
+[#451]: https://github.com/scikit-hep/vector/pull/451
+
 ## Version 1.3
 
 ### Version 1.3.1

docs/usage/intro.ipynb

@@ -573,7 +573,7 @@
    "source": [
     "### SymPy vectors\n",
     "\n",
-    "> Note: In order to allow SymPy simplifications to work effectively, operations on SymPy vectors are a 100% correct only if the vectors are time-like, that is, they lie in the positive time-like cone (`t**2 > x**2 + y**2 + z**2`). Operations on other vectors might output wrong results.\n",
+    "> **Note:** Operations on SymPy vectors are only 100% compatible with numeric vectors (Python, NumPy, and Awkward backends) if the vectors are positive time-like, that is, if `t**2 > x**2 + y**2 + z**2`. The space-like and negative time-like cases have different sign conventions.\n",
     "\n",
     "You can directly use the `VectorSympy` and `MomentumSympy` classes to construct object type vectors:"
    ]