docs(readme): add warning that custom title value should be URL encoded (#4547)

Co-authored-by: Alexandr <qwerty541zxc@gmail.com>

backend/readme.md

@@ -399,6 +399,9 @@ If we don't support your language, please consider contributing! You can find mo
 | `show` | Shows [additional items](#showing-additional-individual-stats) on stats card (i.e. `reviews`, `discussions_started`, `discussions_answered`, `prs_merged` or `prs_merged_percentage`. And the following, which support the `repo` and `owner` filters: `prs_authored`, `prs_commented`, `prs_reviewed`, `issues_authored` or `issues_commented`). | string (comma-separated values) | `null` |
 | `commits_year` | Filters and counts only commits made in the specified year. | integer _(YYYY)_ | `<current year> (one year to date)` |
 
+> [!WARNING]\
+> Custom title should be URI-escaped, as specified in [Percent Encoding](https://en.wikipedia.org/wiki/Percent-encoding) (i.e: `Anurag's GitHub Stats` should become `Anurag%27s%20GitHub%20Stats`). You can use [urlencoder.org](https://www.urlencoder.org/) to help you do this automatically.
+
 > [!NOTE]\
 > When hide\_rank=`true`, the minimum card width is 270 px + the title length and padding.
 
@@ -528,9 +531,7 @@ You can customize the appearance and behavior of the top languages card using th
 | `stats_format` | Switches between two available formats for language's stats `percentages` and `bytes`. | enum | `percentages` |
 
 > [!WARNING]\
-> Language names should be URI-escaped, as specified in [Percent Encoding](https://en.wikipedia.org/wiki/Percent-encoding)
-> (i.e: `c++` should become `c%2B%2B`, `jupyter notebook` should become `jupyter%20notebook`, etc.) You can use
-> [urlencoder.org](https://www.urlencoder.org/) to help you do this automatically.
+> Language names and custom title should be URI-escaped, as specified in [Percent Encoding](https://en.wikipedia.org/wiki/Percent-encoding) (i.e: `c++` should become `c%2B%2B`, `jupyter notebook` should become `jupyter%20notebook`, `Most Used Languages` should become `Most%20Used%20Languages`, etc.) You can use [urlencoder.org](https://www.urlencoder.org/) to help you do this automatically.
 
 ### Language stats algorithm
 
@@ -684,6 +685,9 @@ You can customize the appearance and behavior of the WakaTime stats card using t
 | `display_format` | Sets the WakaTime stats display format. Choose `time` to display time-based stats or `percent` to show percentages. | enum | `time` |
 | `disable_animations` | Disables all animations in the card. | boolean | `false` |
 
+> [!WARNING]\
+> Custom title should be URI-escaped, as specified in [Percent Encoding](https://en.wikipedia.org/wiki/Percent-encoding) (i.e: `WakaTime Stats` should become `WakaTime%20Stats`). You can use [urlencoder.org](https://www.urlencoder.org/) to help you do this automatically.
+
 ### Demo
 
 ![Harlok's WakaTime stats](https://github-readme-stats-phi-jet-58.vercel.app/api/wakatime?username=ffflabs)