doc: fix typos and trailing spaces

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/8285044

doc/code.html

@@ -219,7 +219,7 @@ $ <b>go install</b>
 This command builds the <code>hello</code> command, producing an executable
 binary. It then installs that binary to the workspace's <code>bin</code>
 directory as <code>hello</code> (or, under Windows, <code>hello.exe</code>).
-In our example, tha will be <code>$GOPATH/bin/hello</code>, which is
+In our example, that will be <code>$GOPATH/bin/hello</code>, which is
 <code>$HOME/go/bin/hello</code>.
 </p>
 
@@ -276,7 +276,7 @@ Let's write a library and use it from the <code>hello</code> program.
 </p>
 
 <p>
-Again, the first step is to choose a package path (we'll use 
+Again, the first step is to choose a package path (we'll use
 <code>github.com/user/newmath</code>) and create the package directory:
 </p>
 
@@ -398,7 +398,7 @@ and will reflect the operating system and architecture of your system.
 </p>
 
 <p>
-Go command exectuables are statically linked; the package objects need not
+Go command executables are statically linked; the package objects need not
 be present to run Go programs.
 </p>
 
@@ -535,7 +535,7 @@ tree should now now look like this:
 bin/
     hello                 # command executable
 pkg/
-    linux_amd64/ 
+    linux_amd64/
         code.google.com/p/go.example/
             newmath.a     # package object
         github.com/user/