[mlir] Fix typos in documentation (llvm#110869)

Author: tim-hoffman

mlir/docs/DefiningDialects/Operations.md

@@ -756,7 +756,7 @@ The available directives are as follows:
 
 *   `ref ( input )`
 
-    -   Represents a reference to the a variable or directive, that must have
+    -   Represents a reference to a variable or directive, that must have
         already been resolved, that may be used as a parameter to a `custom`
         directive.
     -   Used to pass previously parsed entities to custom directives.

mlir/docs/DefiningDialects/_index.md

@@ -133,7 +133,7 @@ void MyOp::setOtherValue(StringAttr newValue);
 
 ### Dependent Dialects
 
-MLIR has a very large ecosystem, and contains dialects that server many different purposes. It
+MLIR has a very large ecosystem, and contains dialects that serve many different purposes. It
 is quite common, given the above, that dialects may want to reuse certain components from other
 dialects. This may mean generating operations from those dialects during canonicalization, reusing
 attributes or types, etc. When a dialect has a dependency on another, i.e. when it constructs and/or

mlir/include/mlir/Dialect/Func/IR/FuncOps.td

@@ -251,7 +251,7 @@ def FuncOp : Func_Op<"func", [
 
     // A function that returns its argument twice:
     func.func @count(%x: i64) -> (i64, i64)
-      attributes {fruit: "banana"} {
+      attributes {fruit = "banana"} {
       return %x, %x: i64, i64
     }