Bump version to 0.2.28 and update syntax doc

Cargo.lock

@@ -62,7 +62,7 @@ dependencies = [
 
 [[package]]
 name = "bend-lang"
-version = "0.2.27"
+version = "0.2.28"
 dependencies = [
  "TSPL",
  "clap",

Cargo.toml

@@ -2,7 +2,7 @@
 name = "bend-lang"
 description = "A high-level, massively parallel programming language"
 license = "Apache-2.0"
-version = "0.2.27"
+version = "0.2.28"
 edition = "2021"
 rust-version = "1.74"
 exclude = ["tests/snapshots/"]

docs/syntax.md

@@ -142,6 +142,17 @@ The operations are:
 - Subtraction `-=`
 - Multiplication `*=`
 - Division `/=`
+- Bit And `&=`
+- Bit Or `|=`
+- Bit Xor `^=`
+- Mapper `@=`
+
+The mapper in-place operation applies a function and re-assings the variable:
+
+```python
+x = "hello"
+x @= String/uppercase
+```
 
 ### Return