improve installation guide

doc/installation.md

@@ -23,11 +23,11 @@ To install the code in folder `~/codes/amrvac`:
 
 To use MPI-AMRVAC, the installation directory must be exported as an environment 
 parameter called AMRVAC_DIR and this variable can be added to the command searching path.
-To do so using bash, you should add the following line
-to your `~/.bashrc` file (or perhaps `~/.profile` in mac OS):
+To do so using bash, you should add the following line to your `~/.bashrc` file in b shell linux
+(or `~/.profile` in b shell mac OS, `~/.zshrc` in z shell mac OS):
 
     export AMRVAC_DIR=$HOME/codes/amrvac
-    PATH="$PATH:$HOME/codes/amrvac:$HOME/codes/amrvac/tools"
+    export PATH=$PATH:.:$AMRVAC_DIR:$AMRVAC_DIR/tools
 
 You can then activate the setting by sourcing this file (or you can close and open a new terminal shell), 
 

doc/limiter.md

@@ -15,7 +15,7 @@ Most TVD limiters in mod_limiter.t could be found in Yee (1989).
 
 In the current version, limiters can be chosen from the following list.
 
-Limiter Type | Lmiter | Order | Ghost cells | Reference
+Limiter Type | Limiter | Order | Ghost cells | Reference
 ---|---|---|---|---
 TVD | 'minmod' | 2 | 2 | e.g., Roe (1985), Yee (1989), LeVeque (2002), Toro (2009)
 TVD | 'superbee' | 2 | 2 | Sweby (1984), Roe(1985)