Add get-packages.sh invocation for building from source; fix typo.

Changes to text file README.md only.

README.md

@@ -78,6 +78,9 @@ Before continuing, be sure to prepare Zipr's environment by doing the following:
 ```bash
 cd /path/to/zipr && . set_env_vars
 ```
+```bash
+cd /path/to/zipr && ./get_packages.sh
+```
 
 #### Step 1: Testing Zipr
 Test the binary rewriting infrastructure by rewriting Linux's `ls` binary:
@@ -100,7 +103,7 @@ Performing step zipr [dependencies=clone,fill_in_indtargs,fill_in_cfg,pdb_regist
 ```
 Invoke the rewritten version and make sure it runs normally: 
 ```
-./tmp/ls.zipr
+/tmp/ls.zipr
 ``` 
 
 #### Step 2: Download and build ZAFL
@@ -112,6 +115,10 @@ Second, prepare ZAFL's environment:
 ```bash
 cd /path/to/zafl && . set_env_vars
 ```
+```bash
+cd /path/to/zafl && ./get-packages.sh
+```
+
 Lastly, build ZAFL:
 ```bash
 scons