fix some documentation typos

INSTALL

@@ -120,7 +120,7 @@ main host system library directories.
 
 Finally, it's worth noting that musl's include and lib directories in
 the build tree are setup to be usable without installation, if
-necessary. Just modify the the paths in the spec file used by musl-gcc
+necessary. Just modify the paths in the spec file used by musl-gcc
 (it's located at $prefix/lib/musl-gcc.specs) to point to the
 source/build tree.
 

WHATSNEW

@@ -963,7 +963,7 @@ arch-specific bugs fixed:
 
 0.9.12 release notes
 
-new feastures:
+new features:
 - zoneinfo time zone support
 - PIE support on all supported archs
 - named sub-archs for endian and float ABI variants