reinstate FileTree.md and rename it back to FileTreeDocumentation.md

This reverts deletion in commit 542cede789b8d19c6dda24cddb64710d6ea21700,
and reverts the rename in commit 9c23079eb14032256cad7c9c922a41a3f09be633.

Fixes golang/go#34590

FileTreeDocumentation.md

@@ -0,0 +1,127 @@
+This wiki page documents the file tree for a source installation of go1.9.2 to which have been added the github.com/golang blog, net and tools sub-repositories, and the github.com/gonum/gonum repository. It is somewhat consistent with the file tree of the golang.org/dl pre-compiled downloads for GNU/Linux. It presumes the reader is familiar with utilisation of $GOPATH on Un*x as a colon-separated string; GNU/Linux being a multi-user OS the added sub-repositories and repository are located in $HOME/go and /usr/share/gocode.
+
+```
+% tree -d -L 2 /usr/lib/go1.9.2 | head
+/usr/lib/go1.9.2
+`-- go
+    |-- api
+    |-- bin
+    |-- doc
+    |-- lib
+    |-- misc
+    |-- pkg
+    |-- src
+    `-- test
+%
+```
+
+api contains data for Go's API checker
+
+```
+% ls $GOROOT/api
+README     go1.1.txt  go1.3.txt  go1.5.txt  go1.7.txt go1.9.txt  next.txt
+except.txt  go1.2.txt  go1.4.txt  go1.6.txt  go1.8.txt go1.txt
+%
+```
+
+bin contains the go and gofmt executables
+
+```
+% ls -l $GOROOT/bin
+total 7588
+-rwxr-xr-x 1 root root 5918348 Oct 31 16:06 go
+-rwxr-xr-x 1 root root 1831140 Oct 31 16:06 gofmt
+%
+```
+
+doc contains .css, .go, .html, .js, and .png files
+
+lib contains the compressed time zone database
+
+```
+% tree $GOROOT/lib | head -n 5
+/usr/lib/go1.9.2/go/lib
+`-- time
+|-- README
+|-- update.bash
+`-- zoneinfo.zip
+%
+```
+
+misc/android contains information on development for android<br/>
+misc/arm contains a script for executing go binaries on android<br/>
+misc/cgo contains tests and examples of cgo<br/>
+misc/chrome contains a Chrome extension<br/>
+misc/git contains a pre-commit hook<br/>
+misc/ios contains information on cross compiling for iOS<br/>
+misc/linkcheck contains a program checking links on the godoc website<br/>
+misc/nacl contains Go's integration with nacl, used by the Go playground<br/>
+misc/sortac contains a utility for sorting the AUTHORS and CONTRIBUTORS files<br/>
+misc/swig contains examples of using Go with SWIG<br/>
+misc/trace contains a generated file used by go tool trace
+
+```
+% tree -d -L 1 $GOROOT/misc | head -n 12
+/usr/lib/go1.9.2/go/misc
+|-- android
+|-- arm
+|-- cgo
+|-- chrome
+|-- git
+|-- ios
+|-- linkcheck
+|-- nacl
+|-- sortac
+|-- swig
+`-- trace
+%
+```
+
+pkg contains libs, header files, compiled object files, and executables
+
+```
+% tree -d -L 1 $GOROOT/pkg | head -n 7
+/usr/lib/go1.9.2/go/pkg
+|-- bootstrap
+|-- include
+|-- linux_386
+|-- linux_386_dynlink
+|-- obj
+`-- tool
+%
+```
+
+test contains tests of the Go tool chain and runtime
+
+The github.com/golang net and tools sub-repositories and github.com/gonum/gonum repository can be located in /usr/share/gocode, utilising the following commands.
+
+```
+% su -c tcsh
+Password:
+# setenv GOPATH /usr/share/gocode
+# go get -u golang.org/x/tools/...
+# go get -u gonum.org/v1/gonum/...
+# find $GOPATH -print0 | xargs -0 file | grep "executable" | grep ELF \
+? | cut -f 1 -d : | xargs strip --strip-unneeded
+# exit
+%
+```
+
+To compile Go code with the libraries in /usr/share/gocode you must add the location to $GOPATH.
+
+```
+% setenv GOPATH $HOME/go:/usr/share/gocode
+% go get -u golang.org/x/blog
+package golang.org/x/blog: no Go files in /home/eric/go/src/golang.org/x/blog
+% cd go/src/golang.org/x/blog/blog
+% go build
+% mv blog $HOME/go/bin
+%
+```
+
+This page utilises the C shell as [SettingGOPATH](https://github.com/golang/go/wiki/SettingGOPATH) doesn't include that shell.
+
+For information on running the blog server see [Go Blog](https://github.com/golang/blog); those instructions might be more comprehensive being edited, but for Un*x just omit the .exe
+file extension.
+
+See also: [Modules](https://github.com/golang/go/wiki/modules)