[file-roller] Fix two typos in README_COMMANDLINE

[Andre Klapper <aklapper src gnome org>]

commit 62700d82c1c3bb1cf9eeb64ebeb36bad76548fbd
Author: Mithil Poojary <mithil467 gmail com>
Date:   Mon Nov 25 04:48:10 2019 +0100

    Fix two typos in README_COMMANDLINE
    
    Fixes #58

 README_COMMANDLINE | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/README_COMMANDLINE b/README_COMMANDLINE
index c7ea5694..ee864abc 100644
--- a/README_COMMANDLINE
+++ b/README_COMMANDLINE
@@ -36,11 +36,11 @@ You can extract a series of archives with a single command.
 Compression
 -----------
 
-1) Compress a series of files specifing the archive name:
+1) Compress a series of files specifying the archive name:
 
        file-roller --add-to=/path/to/archive.tgz file1 file2 ..
 
-   the archive is created if it doesn't exit.
+   the archive is created if it doesn't exist.
 
 2) Compress a series of files letting the user choose the archive name: