update readme

README.md

@@ -40,7 +40,7 @@ The `manual_build.sh` script can be used to generate the PDF version of manual(s
 ./manual_build.sh [-c] [-p] [-r version ] manual_name
 ```
 
-`manual_name` : Chose one model manual among `NEMO`, `SI3`, `TOP`, or `all` (if not provided compile `NEMO`)
+`manual_name` : Chose one model manual among `NEMO`, `SI3`, `TOP`, or `all` (if not provided, it will compile `NEMO`)
 
 Optional commands :
 
@@ -52,5 +52,8 @@ Optional commands :
 
 ### Known troubles
 
+**`./manual_build.sh` must be called several times in a row (up to 4 times) to avoid all the errors messages and get the proper pdf.**.
+
 If you get an error due to the missing location of `FontAwesome`, it is necessary to set the local path 
 of LaTeX fonts in the file `latex/global/packages.tex` at `\defaultfontfeatures`. Be carefull not to commit this modification to the remote code.
+