fix typo in 11.

11_install_system_programs.md

@@ -15,7 +15,7 @@ However, interdependencies between programs and libraries can be a nightmare to
 System-wide installation steps:
 
 - The user asks the package manager to install a program
-- The** package manager** queries its repository lists to search for the most recent **package** version of the program (or a specific version)
+- The **package manager** queries its repository lists to search for the most recent **package** version of the program (or a specific version)
 - The **package manager** construct the dependency tree of the program
 - The **package manager** check that the new dependency tree is compatible with every other installed program
 - The **package manager** install the program **package** and all it’s dependencies **packages** in their correct version
@@ -64,7 +64,7 @@ You can check the list of repositories that `apt` checks in the file `/etc/apt/s
 You can add the official cran repository to your repositories list:
 
 ```sh
-sudo add-apt-repository 'deb https://cloud.r-project.org/bin/linux/ubuntu <release_name>-cran35/'
+sudo add-apt-repository 'deb https://cloud.r-project.org/bin/linux/ubuntu <release_name>-cran40/'
 ```
 
 You can use the command `lsb_release -sc` to get your **release name**.
@@ -115,7 +115,7 @@ sudo apt search linux-image
 
 If it’s not a good idea to have different **package manager** on the same system (they don’t know how the dependencies are handled by the other’s manager). You will also encounter language specific package manager:
 
-- `ppm` for Pperl
+- `ppm` for Perl
 - `pip` for Python
 - `npm` for JavaScript
 - `cargo` for Rust
@@ -219,7 +219,7 @@ You can finalize the installation with the command `make install`. Usually the c
 
 Read the `README` file of the [fastp](https://github.com/OpenGene/fastp) program to see which methods of installation are available.
 
-Installing programs and maintain different versions of a program on the same system, is a difficult task. In the next session, we will learn how to use [virtualisation](http://perso.ens-lyon.fr/laurent.modolo/unix/12_virtualisation.html) to facilitate our job.
+Installing programs and maintain different versions of a program on the same system, is a difficult task. In the next session, we will learn how to use [virtualization](http://perso.ens-lyon.fr/laurent.modolo/unix/12_virtualization.html) to facilitate our job.
 
 > We have used the following commands:
 >