Fix various typos in lint messages, descriptions and comments

clippy_utils/src/str_utils.rs

@@ -1,4 +1,4 @@
-/// Dealing with sting indices can be hard, this struct ensures that both the
+/// Dealing with string indices can be hard, this struct ensures that both the
 /// character and byte index are provided for correct indexing.
 #[derive(Debug, Default, PartialEq, Eq)]
 pub struct StrIndex {
@@ -165,7 +165,7 @@ pub fn camel_case_split(s: &str) -> Vec<&str> {
     offsets.windows(2).map(|w| &s[w[0]..w[1]]).collect()
 }
 
-/// Dealing with sting comparison can be complicated, this struct ensures that both the
+/// Dealing with string comparison can be complicated, this struct ensures that both the
 /// character and byte count are provided for correct indexing.
 #[derive(Debug, Default, PartialEq, Eq)]
 pub struct StrCount {

clippy_utils/src/ty/mod.rs

@@ -1352,7 +1352,7 @@ pub fn get_adt_inherent_method<'a>(cx: &'a LateContext<'_>, ty: Ty<'_>, method_n
     }
 }
 
-/// Get's the type of a field by name.
+/// Gets the type of a field by name.
 pub fn get_field_by_name<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, name: Symbol) -> Option<Ty<'tcx>> {
     match *ty.kind() {
         ty::Adt(def, args) if def.is_union() || def.is_struct() => def