Fix typos (#137)

Found via `typos --hidden --format brief`

README.md

@@ -7,7 +7,7 @@
 `NimbleParsec` is a simple and fast library for text-based parser
 combinators.
 
-Combinators are composed programatically and compiled into multiple
+Combinators are composed programmatically and compiled into multiple
 clauses with binary matching. This provides the following benefits:
 
   * Performance: since it compiles to binary matching, it leverages

lib/nimble_parsec.ex

@@ -1520,7 +1520,7 @@ defmodule NimbleParsec do
   **Note:** this can be potentially a very expensive operation
   as it executes the given combinator byte by byte until finding
   an eventual match or ultimately failing. For example, if you
-  are looking for an integer, it is preferrable to discard
+  are looking for an integer, it is preferable to discard
   everything that is not an integer
 
       ignore(ascii_string([not: ?0..?9]))

test/nimble_parsec_test.exs

@@ -1474,7 +1474,7 @@ defmodule NimbleParsecTest do
       assert parse_bytes("abc") == {:ok, ["abc"], "", %{}, {1, 0}, 3}
     end
 
-    test "fails if input has insufficent bytes" do
+    test "fails if input has insufficient bytes" do
       assert parse_bytes("ab") == {:error, "expected 3 bytes", "ab", %{}, {1, 0}, 0}
     end
   end