Update installation instructions

doc/src/installation.md

@@ -5,50 +5,43 @@
 This is the easiest way.
 
 Install prerequisites and LFortran (works on both Linux and Mac):
-```
+```bash
 conda create -n lfortran python=3.7 pytest llvmlite prompt_toolkit
 conda activate lfortran
 pip install antlr4-python3-runtime
 tar xzf lfortran-0.1.tar.gz
 cd lfortran-0.1
 pip install .
 ```
-
 Now the `lfortran` environment has the `lfort` compiler available.
 
 Optional: run tests:
-```
+```bash
 py.test --pyargs lfortran
 ```
 
 
 ## From Git
 
 This works both on Linux and a Mac:
-
-```
+```bash
 conda create -n lfortran python=3.7 pytest llvmlite prompt_toolkit
 conda activate lfortran
 pip install antlr4-python3-runtime
 ```
-
 Install Java and then ANTLR, say, into `~/ext`:
-```
+```bash
 export CLASSPATH="$HOME/ext/antlr-4.7-complete.jar:$CLASSPATH"
 ```
-
 Build:
-```
+```bash
 ./build.sh
 ```
-
 Run tests:
-
-```
+```bash
 py.test
 ```
-
-Run prompt:
-```
-./prompt
+Run an interactive prompt:
+```bash
+./lfort
 ```