cmd/compile: fix wording in README

"Syntax analysis" sounds more familiar and fits the
item before, which says "lexical analysis".
If there was specific intention to the original wording,
I, as a reader, would like to see it instead of this
confusing wording.

Change-Id: Id32dbf75300a86b21cb9f35e54526184fe5df6cb
Reviewed-on: https://go-review.googlesource.com/117696Reviewed-by: Robert Griesemer <gri@golang.org>

src/cmd/compile/README.md

@@ -26,7 +26,7 @@ little to do with uppercase GC, which stands for garbage collection.
 * `cmd/compile/internal/syntax` (lexer, parser, syntax tree)
 
 In the first phase of compilation, source code is tokenized (lexical analysis),
-parsed (syntactic analyses), and a syntax tree is constructed for each source
+parsed (syntax analysis), and a syntax tree is constructed for each source
 file.
 
 Each syntax tree is an exact representation of the respective source file, with