CLDR-18938 Add message format to spec modifications (#5088)

Co-authored-by: Annemarie Apple <[email protected]>
Co-authored-by: Fredrik <[email protected]>

Author: 3 people

docs/ldml/tr35-modifications.md

@@ -83,13 +83,27 @@ The order of execution is also clearly specified.
 The rules have been converted to a “flat” format, which is easier for clients to handle (the old format will be retained for one more release).
 
 ### Units of Measurement
-* [Unit Syntax](tr35-general.md#unit-syntax) Simplified the EBNF `product_unit`, and added an additional well-formedness constraint for a mixed units.
+* [Unit Syntax](tr35-general.md#unit-syntax) Simplified the EBNF `product_unit` and added an additional well-formedness constraint for mixed units.
 * [Unit Identifier Normalization](#tr35-general.md) Modified the normalization process
 * [Mixed Units](tr35-general.md#mixed-units) Modified the guidance for handling precision.
 
 ### Collation
 * [Collation](tr35-collation.md) Added the new `FractionalUCA_blanked.txt` to the root collation data files.
 
+### MessageFormat
+#### Normative changes to Stable parts of the specification:
+* Syntax and data model errors now must be prioritized over other errors ([\#1011](https://github.com/unicode-org/message-format-wg/pull/1011))  
+* The Default Bidi Strategy is now required and default ([\#1066](https://github.com/unicode-org/message-format-wg/pull/1066))  
+* The `:offset` function (previously named `:math`) is now available as Stable ([\#1073](https://github.com/unicode-org/message-format-wg/pull/1073))
+
+#### Normative changes to Draft parts of the specification:
+* The `:datetime`, `:date`, and `:time` functions are updated to build on top of semantic skeletons ([\#1078](https://github.com/unicode-org/message-format-wg/pull/1078), [\#1083](https://github.com/unicode-org/message-format-wg/pull/1083))  
+* `:percent` is added as a new Draft function ([\#1094](https://github.com/unicode-org/message-format-wg/pull/1094))
+
+#### Editorial changes:
+* The format is more clearly rebranded as "Unicode MessageFormat" ([\#1064](https://github.com/unicode-org/message-format-wg/pull/1064))  
+* The pattern selection definition is refactored to be easier to understand without changing its meaning ([\#1080](https://github.com/unicode-org/message-format-wg/pull/1080))
+
 ### Keyboards
 __TBD Needs some cleanup for consistency__
 * A sentence was struck under the documentation of the [display](tr35-keyboards.md#element-display) element.