[Doc] Fix manual install & upgrade guide, fix #1772

README.md

@@ -149,7 +149,7 @@ For a fully manual install, create a folder somewhere in your filesystem with th
 export NVM_DIR="$HOME/.nvm" && (
   git clone https://github.com/creationix/nvm.git "$NVM_DIR"
   cd "$NVM_DIR"
-  git checkout `git describe --abbrev=0 --tags --match "v[0-9]*" origin`
+  git checkout `git describe --abbrev=0 --tags --match "v[0-9]*" $(git rev-list --tags --max-count=1)`
 ) && \. "$NVM_DIR/nvm.sh"
 ```
 
@@ -174,7 +174,7 @@ For manual upgrade with `git` (requires git v1.7.10+):
 (
   cd "$NVM_DIR"
   git fetch origin
-  git checkout `git describe --abbrev=0 --tags --match "v[0-9]*" origin`
+  git checkout `git describe --abbrev=0 --tags --match "v[0-9]*" $(git rev-list --tags --max-count=1)`
 ) && \. "$NVM_DIR/nvm.sh"
 ```