[WALLPAPERS] Update README.md for wallpapers manage (#5)

- Add "Manage this repository" section in
  README.md.
- Add "File size" section in README.md.
- Rename roswallp.txt as roswallp-sample.txt
  to avoid confusion.

Author: katahiromz

README.md

@@ -23,3 +23,24 @@ You can download these wallpapers from the "ReactOS Standard Wallpapers" package
 | ReactOS_Mizu_16x9_A.png            | See above                                     | See above                                                  |
 | ReactOS_Mizu_16x9_B.png            | See above                                     | See above                                                  |
 | Silhouette collection              | Jake Collins (polar@ever3st.com)              | https://ever3st.com/Graphics/Loot/                         |
+
+## File size
+
+The file size of one wallpaper file should be smaller than 300 KB. The recommended size is 150 KB or smaller.
+
+## Manage this repository
+
+### Who is the wallpaper manager?
+
+- Current wallpaper manager: https://reactos.com/katahiromz
+
+### The job of the wallpaper manager
+
+If any changes are made to the `wallpapers` repository, then the wallpaper manager has to update `roswallp.txt` in `reactos/rapps-db`, for downloading "ReactOS Standard Wallpapers" package (`roswallp`), as follows:
+
+1. Hold a poll or create a pull request before making any significant changes to the `wallpapers` repository.
+2. Update the `wallpapers` repository.
+3. Run `./make-zip.sh` on the latest `wallpapers` local repository.
+4. The file `output/wallpapers.zip` will be generated.
+5. Release the new `wallpapers.zip` on the `reactos/wallpapers` `Releases` page ( https://github.com/reactos/wallpapers/releases ) with a new version tag (`v???`).
+6. Update the data file `roswallp.txt` on `reactos/rapps-db` by comparing it with this repository's [`roswallp-sample.txt`](roswallp-sample.txt) (See `TODO:` parts).

roswallp.txt roswallp-sample.txtroswallp.txt renamed to roswallp-sample.txt

@@ -1,13 +1,13 @@
 [Section]
 Name = ReactOS Standard Wallpapers
-Version = ???
+Version = (TODO: Version number in digits only)
 License = CC BY
 Description = The standard wallpaper collection for ReactOS
 Category = 16
 URLSite = https://github.com/reactos/wallpapers/
-URLDownload = https://github.com/reactos/wallpapers/releases/download/???/wallpapers.zip
+URLDownload = https://github.com/reactos/wallpapers/releases/download/v(TODO: Version number)/wallpapers.zip
 Installer = Generate
-SizeBytes = ???
+SizeBytes = (TODO: File size in digits only)
 
 [Generate]
 Files = *