Replace the README with a README.md

Also include the `go mod tidy` detail.

Signed-off-by: Andrew G. Morgan <morgan@kernel.org>
diff --git a/goapps/web/README b/goapps/web/README
deleted file mode 100644
index cbabd5d..0000000
--- a/goapps/web/README
+++ /dev/null
@@ -1,18 +0,0 @@
-This sample program needs to be built as follows (when built with Go
-prior to 1.15):
-
-   CGO_LDFLAGS_ALLOW="-Wl,-?-wrap[=,][^-.@][^,]*" go build web.go
-
-go1.15+ does not require the CGO_LDFLAGS_ALLOW variable and can build
-this code with
-
-   go build web.go
-
-A more complete walk through of what this code does is provided here:
-
-   https://sites.google.com/site/fullycapable/getting-started-with-go/building-go-programs-that-manipulate-capabilities
-
-Go compilers prior to go1.11.13 are not expected to work. Report more
-recent issues to:
-
-   https://bugzilla.kernel.org/buglist.cgi?component=libcap&list_id=1065141&product=Tools&resolution=---
diff --git a/goapps/web/README.md b/goapps/web/README.md
new file mode 100644
index 0000000..970d10e
--- /dev/null
+++ b/goapps/web/README.md
@@ -0,0 +1,28 @@
+# Web serving with/without privilege
+
+## Building
+
+This sample program needs to be built as follows (when built with Go
+prior to 1.15):
+```
+   export CGO_LDFLAGS_ALLOW="-Wl,-?-wrap[=,][^-.@][^,]*"
+   go mod tidy
+   go build web.go
+```
+go1.15+ does not require the `CGO_LDFLAGS_ALLOW` environment variable
+and can build this code with:
+```
+   go mod tidy
+   go build web.go
+```
+
+## Further discussion
+
+A more complete walk through of what this code does is provided on the
+[Fully Capable
+website](https://sites.google.com/site/fullycapable/getting-started-with-go/building-go-programs-that-manipulate-capabilities).
+
+## Reporting bugs
+
+Go compilers prior to go1.11.13 are not expected to work. Report more
+recent issues to the [`libcap` bug tracker](https://bugzilla.kernel.org/buglist.cgi?component=libcap&list_id=1065141&product=Tools&resolution=---).
diff --git a/goapps/web/web.go b/goapps/web/web.go
index c96e745..5f9c5cb 100644
--- a/goapps/web/web.go
+++ b/goapps/web/web.go
@@ -13,6 +13,8 @@
 // package - go versions prior to 1.15 need some environment variable
 // workarounds):
 //
+//   go mod init web
+//   go mod tidy
 //   go build web.go
 //   sudo setcap cap_setpcap,cap_net_bind_service=p web
 //   ./web --port=80