chore: minor improvement for docs (#790)

Signed-off-by: claudecodering <claudecoder@outlook.com>

Author: claudecodering

src/header/name.rs

@@ -1245,7 +1245,7 @@ impl HeaderName {
     /// ```should_panic
     /// # use http::header::*;
     /// #
-    /// // Parsing a header that contains invalid symbols(s):
+    /// // Parsing a header that contains invalid symbols:
     /// HeaderName::from_static("content{}{}length"); // This line panics!
     ///
     /// // Parsing a header that contains invalid uppercase characters.

src/header/value.rs

@@ -15,7 +15,7 @@ use crate::header::name::HeaderName;
 /// HTTP spec allows for a header value to contain opaque bytes as well. In this
 /// case, the header field value is not able to be represented as a string.
 ///
-/// To handle this, the `HeaderValue` is useable as a type and can be compared
+/// To handle this, the `HeaderValue` is usable as a type and can be compared
 /// with strings and implements `Debug`. A `to_str` fn is provided that returns
 /// an `Err` if the header value contains non visible ascii characters.
 #[derive(Clone)]