Minor spelling fixes

src/libstd/fs.rs

@@ -521,7 +521,7 @@ impl OpenOptions {
     /// No file is allowed to exist at the target location, also no (dangling)
     /// symlink.
     ///
-    /// This option is usefull because it as atomic. Otherwise between checking
+    /// This option is useful because it as atomic. Otherwise between checking
     /// whether a file exists and creating a new one, the file may have been
     /// created by another process (a TOCTOU race condition / attack).
     ///

src/libstd/memchr.rs

@@ -150,7 +150,7 @@ mod fallback {
         // Scan for a single byte value by reading two `usize` words at a time.
         //
         // Split `text` in three parts
-        // - unaligned inital part, before the first word aligned address in text
+        // - unaligned initial part, before the first word aligned address in text
         // - body, scan by 2 words at a time
         // - the last remaining part, < 2 word size
         let len = text.len();

src/libstd/panic.rs

@@ -84,7 +84,7 @@ pub use panicking::{take_handler, set_handler, PanicInfo, Location};
 /// recover safe. The general idea is that any mutable state which can be shared
 /// across `recover` is not recover safe by default. This is because it is very
 /// easy to witness a broken invariant outside of `recover` as the data is
-/// simply accesed as usual.
+/// simply accessed as usual.
 ///
 /// Types like `&Mutex<T>`, however, are recover safe because they implement
 /// poisoning by default. They still allow witnessing a broken invariant, but