[fractal.wiki] Improve grammar

[Alexandre Franke <afranke src gnome org>]

commit a4bbd1a0309c75166f845cb20cfee0bf779f3540
Author: Alexandre Franke <afranke gnome org>
Date:   Wed Dec 2 23:58:22 2020 +0100

    Improve grammar

 Best-practices-for-Fractal-development.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/Best-practices-for-Fractal-development.md b/Best-practices-for-Fractal-development.md
index 14b745c..5510d16 100644
--- a/Best-practices-for-Fractal-development.md
+++ b/Best-practices-for-Fractal-development.md
@@ -18,6 +18,6 @@ If a merge request makes visible UI changes, include screenshots (or a screencas
 * Use `.unwrap_or_default()` for `Option` and `Result` over `unwrap_or(neutral_value)`. It won't work if the 
contained type doesn't implement the Default trait.
 * Prefer to process the contained value in an Option or Result with combinators and unwrap at the end, 
unless it makes the code difficult to read because of doing it that way.
 * Don't be afraid to go beyond the simpler types or even create new ones. They give semantic meaning to 
values and thus let the compiler check for the correctness of the code at that level if used appropriately.
-* AppOp is a legacy struct which shouldn't be used anymore in new code, we work on removing it.
+* AppOp is a legacy struct which shouldn't be used anymore in new code, we are working on removing it.
 * In fractal-gtk we depend on gtk and glib, try to use glib methods to solve problems where ever possible.