fix doc

README.md

@@ -12,13 +12,17 @@ The command line tools are strongly linked with the CrestApi library, thus we su
 1. **Clone CrestApi package**:
    ```shell
    git clone https://gitlab.cern.ch/crest-db/CrestApi.git
+   cd CrestApi
    git fetch
    git switch release-5.1-CR1
    ```
    You should then install locally the CrestApi lib following the instructions in the readme.
-   In general:
+   In general you need to prepare an installation directory (if not existing):
    ```shell
    mkdir $HOME/installed
+   ```
+   Now you can build the project and install it:
+   ```shell
    cd <CrestApi directory>
    mkdir build ; cd build
    cmake -DCMAKE_INSTALL_PREFIX=$HOME/installed ..
@@ -28,6 +32,7 @@ The command line tools are strongly linked with the CrestApi library, thus we su
 2. **Clone CrestCmd package**:
    ```shell
    git clone https://gitlab.cern.ch/crest-db/crest-cmd.git
+   cd crest-cmd
    git fetch
    git switch release-5.1
    ```