docs: specify master for tutorials (#5822)

## Description

Specify master for tutorials. 

I will have a followup PR for 0.34 that specifies 0.34

Ref: #5735

docs/tutorials/go-built-in.md

@@ -40,7 +40,7 @@ Verify that you have the latest version of Go installed:
 
 ```bash
 $ go version
-go version go1.15.1 darwin/amd64
+go version go1.15.x darwin/amd64
 ```
 
 ## 1.2 Creating a new Go project
@@ -579,7 +579,13 @@ go mod init github.com/me/example
 ```
 
 This should create a `go.mod` file. The current tutorial only works with
-tendermint > v0.34, so let's make sure we're using the latest version:
+the master branch of Tendermint. so let's make sure we're using the latest version:
+
+```sh
+go get github.com/tendermint/tendermint@master
+```
+
+This will populate the `go.mod` with a release number followed by a hash for Tendermint.
 
 ```go
 module github.com/me/example
@@ -588,7 +594,7 @@ go 1.15
 
 require (
 	github.com/dgraph-io/badger v1.6.2
-	github.com/tendermint/tendermint v0.34.0-rc4
+	github.com/tendermint/tendermint <vX>
 )
 ```
 

docs/tutorials/go.md

@@ -43,7 +43,7 @@ Verify that you have the latest version of Go installed:
 
 ```bash
 $ go version
-go version go1.15.1 darwin/amd64
+go version go1.15.x darwin/amd64
 ```
 
 ## 1.2 Creating a new Go project
@@ -435,7 +435,13 @@ go mod init github.com/me/example
 ```
 
 This should create a `go.mod` file. The current tutorial only works with
-tendermint > v0.34, so let's make sure we're using the latest version:
+the master branch of Tendermint, so let's make sure we're using the latest version:
+
+```sh
+go get github.com/tendermint/tendermint@master
+```
+
+This will populate the `go.mod` with a release number followed by a hash for Tendermint.
 
 ```go
 module github.com/me/example
@@ -444,7 +450,7 @@ go 1.15
 
 require (
 	github.com/dgraph-io/badger v1.6.2
-	github.com/tendermint/tendermint v0.34.0-rc4
+	github.com/tendermint/tendermint <vX>
 )
 ```