[x/tour] content: make welcome/3 slide more beginner friendly

Re-add the link to installing Go on the welcome/3 slide,
because it's a pre-requisite for being able to run go get.

This was included before, but got lost in a refactor after
the tour binary moved out of the Go distribution.

Additionally, make it more clear that installing the tour
locally is an optional step that only needs to be done if
one wishes to run the tour offline; it's not mandatory to
get through the tour. Running the tour online has a lower
overhead, and should help keep the tour accessible to more
people.

Fixes golang/go#34585
Updates golang/go#24819

Change-Id: If5f51e9e876722a86afca054bf78428f78bb3076
Reviewed-on: https://go-review.googlesource.com/c/tour/+/197857
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
X-Tour-Commit: 45121acd746573507cdaaf902958dba082f7c25b

tour/README.md

@@ -6,12 +6,13 @@ https://tour.golang.org to start the tour.
 ## Download/Install
 
 To install the tour from source, first
-[set up a workspace](https://golang.org/doc/code.html) and then run:
+[install Go](https://golang.org/doc/install) and then run:
 
 	$ go get golang.org/x/tour
 
-This will place a `tour` binary in your workspace's `bin` directory, which
-can be run offline.
+This will place a `tour` binary in your
+[workspace](https://golang.org/doc/code.html#Workspaces)'s `bin` directory.
+The tour program can be run offline.
 
 ## Contributing
 

tour/content/welcome.article

@@ -69,23 +69,23 @@ The tour is available in other languages:
 
 Click the [[javascript:highlightAndClick(".next-page")]["next"]] button or type `PageDown` to continue.
 
-#appengine: * Go offline
+#appengine: * Go offline (optional)
 #appengine:
 #appengine: This tour is also available as a stand-alone program that you can use
-#appengine: without access to the internet.
+#appengine: without access to the internet. It builds and runs the code samples on
+#appengine: your own machine.
 #appengine:
-#appengine: The stand-alone tour is faster, as it builds and runs the code samples
-#appengine: on your own machine.
-#appengine:
-#appengine: To run the tour locally install and run the tour binary:
+#appengine: To run the tour locally, you'll need to first
+#appengine: [[https://golang.org/doc/install][install Go]] and then run:
 #appengine:
 #appengine:   go get golang.org/x/tour
-#appengine:   tour
 #appengine:
-#appengine: The tour program will open a web browser displaying
+#appengine: This will place a `tour` binary in your
+#appengine: [[https://golang.org/doc/code.html#Workspaces][workspace]]'s `bin` directory.
+#appengine: When you run the tour program, it will open a web browser displaying
 #appengine: your local version of the tour.
 #appengine:
-#appengine: Or, of course, you can continue to take the tour through this web site.
+#appengine: Of course, you can continue to take the tour through this web site.
 
 #appengine: * The Go Playground
 #appengine: