[doc] update links, fix typos, rewrite some parts

CONTRIBUTING.md

@@ -19,7 +19,7 @@ There are several ways to participate in the Frama-C project:
 - [Developing external plug-ins](#developing-external-plug-ins)
   and sharing it with us through a Gitlab merge request;
 
-- Joining the [Frama-C team](https://frama-c.com/about.html) (as an intern, a PhD
+- [Joining the Frama-C team](https://frama-c.com/html/jobs.html) (as an intern, a PhD
   student, a postdoctoral researcher, or a research engineer).
 
 We give below some guidelines in order to ease the submission of a merge request
@@ -35,6 +35,10 @@ by following the recommended workflow in git development:
 fork the frama-c repository, develop in a dedicated branch
 and submit a merge request.
 
+Note: these steps assume that you have an account in Frama-C's Gitlab instance.
+This can be done by signing in via Github (which, in turn, requires a Github
+account; if you do not have a Github account, please contact us by e-mail).
+
 The detailed steps to submit a contribution to Frama-C are:
 
 1. If you plan to make a significant contribution to Frama-C, please
@@ -44,7 +48,7 @@ The detailed steps to submit a contribution to Frama-C are:
 2. [Fork the public Frama-C repository](https://git.frama-c.com/pub/frama-c/-/forks/new)
   (choosing your Gitlab account as a destination);
 
-3. Clone the forked Frama-C snapshot repository on your computer;
+3. Clone the forked Frama-C repository on your computer;
 
 4. Create and switch to a dedicated branch. We suggest the following
    naming convention:
@@ -70,33 +74,33 @@ The detailed steps to submit a contribution to Frama-C are:
   problems if any.
 
   Use the command `make check-headers` in your terminal from the Frama-C root
-  directory to detect bad file license (headache is needed), and `make headers`
-  to fix them.
+  directory to detect incorrect file licenses (the `headache` opam package is
+  needed), and `make headers` to fix them.
 
 8. Locally run the test framework of Frama-C by typing
   `make tests`
-  in your terminal (you should be in the Frama-C root directory);
+  in your terminal (you should be in the Frama-C root directory).
 
-9. Locally add (if needed) and commit your contribution;
+9. Locally add (if needed) and commit your contribution.
 
-10. Push your contribution to Gitlab;
+10. Push your contribution to Gitlab.
 
 11. [Make a Gitlab merge request](https://git.frama-c.com/pub/frama-c/merge_requests).
   The target should remain as repository `pub/frama-c` and branch `master`
   while the source should be your personal project and your chosen branch
   name.
 
-12. If needed (i.e. you didn't already do that and your contribution is
-    not trivial in the sense of [this document](TCA.md)), please don't forget
-    to fill and sign the [Contributor Licence Agreement](CLA.pdf) and send us
-    the signed version at `cla AT frama-c DOT com`
+12. If needed (i.e. it is your first non-trivial contribution in the sense of
+  [this document](TCA.md)), please do not forget to fill and sign the
+  [Contributor Licence Agreement](CLA.pdf) and send us the signed version at
+  `cla AT frama-c DOT com`.
 
 For convenience, we recall the typical `git` commands to be used through these steps:
 ```shell
 git clone https://git.frama-c.com/<username>/frama-c.git
 git checkout -b <branch-name>
 git diff --check
-git add <file1 file 2>
+git add <file1 file2 ...>
 git commit -m "<Commit message>"
 git push origin <branch-name>
 ```
@@ -104,7 +108,7 @@ where:
 
 - `<username>` is your Gitlab username;
 - `<branch-name>` is your chosen branch name;
-- `<file1 file2>` are the files to add to the commit;
+- `<file1 file2 ...>` are the files to add to the commit;
 - `<Commit message>` is your commit message.
 
 

README.md

@@ -32,7 +32,7 @@ OCaml package manager. If you have it, simply run:
 
     opam install frama-c
 
-or, for `opam` versions less than 2.1.0:
+or, for `opam` versions less than 2.1:
 
     opam install depext # handles external (non-OCaml) dependencies
     opam depext frama-c --install
@@ -70,11 +70,13 @@ Frama-C can be run from the command-line, or via its graphical interface.
 The recommended usage for simple files is one of the following lines:
 
     frama-c file.c -<plugin> [options]
-    frama-c-gui file.c
+    ivette file.c -<plugin> [options]
 
 Where `-<plugin>` is one of the several Frama-C plug-ins,
 e.g. `-eva`, or `-wp`, or `-metrics`, etc.
-Plug-ins can also be run directly from the GUI.
+Plug-ins can also be run directly from the graphical interface,
+`ivette`.
+A legacy version of the GUI (`frama-c-gui`) is also available.
 
 To list all plug-ins, run:
 
@@ -91,23 +93,23 @@ is available through
 
 #### Complex scenarios
 
-For more complex usage scenarios (lots of files and directories,
-with several preprocessing directives), we recommend splitting Frama-C's usage
-in two parts:
+For complex usage scenarios (several files and directories,
+preprocessing directives, etc), we recommend the following two-step approach:
 
 1. Parsing the input files and saving the result to a file;
 2. Loading the parsing results and then running the analyses or the GUI.
 
-Parsing typically involves giving extra arguments to the C preprocessor,
-so the `-cpp-extra-args` option is often useful, as in the example below:
+Parsing complex C applications usually involves C preprocessor options
+(e.g. GCC's `-D` and `-I`).
+In Frama-C, they are passed via option `-cpp-extra-args`, as in this example:
 
-    frama-c *.c *.h -cpp-extra-args="-D<define> -I<include>" -save parsed.sav
+    frama-c *.c -cpp-extra-args="-D<define> -I<include>" -save parsed.sav
 
-The results are then loaded into Frama-C for further analyses or for inspection
+The results can then be loaded into Frama-C for further analyses or for inspection
 via the GUI:
 
     frama-c -load parsed.sav -<plugin> [options]
-    frama-c-gui -load parsed.sav -<plugin> [options]
+    ivette -load parsed.sav -<plugin> [options]
 
 ## Further reference