Adding an extra element to view README called `ReadMePath`

[hien-ngo29]

Problem:

• Some people are not using Github to store their code
• Readme won't show up. Because the program uses Github API to get the README.

Solution:
Add one more element to the Modlinks manifest called ReadMePath, which contains the URL to the raw file content of readme.

Example:

<Manifest>
    <Name>Vietnamese Lang</Name>
    <Description>Add Vietnamese Language. Hollow Knight Việt Hoá</Description>
    <Version>1.0.1.0</Version>
    <Link SHA256="83c6c677c27c60173b384422e47ca8cd40a2dc7349aa0e65975f8bcc49d2c3fe"><![CDATA[https://codeberg.org/hien-ngo29/HollowKnightVietnameseLangMod/releases/download/v1.0.1.0/HKVietHoa.zip]]></Link>
    <Dependencies>
        <Dependency>LanguageSupport</Dependency>
    </Dependencies>
    <Repository><![CDATA[https://codeberg.org/hien-ngo29/HollowKnightVietnameseLangMod]]></Repository>
    <Tags>
        <Tag>Gameplay</Tag>
    </Tags>
    <Authors>
        <Author>Hien Ngo</Author>
    </Authors>
    <ReadMePath>
        <![CDATA[https://codeberg.org/hien-ngo29/HollowKnightVietnameseLangMod/raw/branch/main/README.md]]>
    </ReadMePath>
</Manifest>

Giving the ReadMePath is optional. If it doesn't exist, it will get the readme content from the repository using Github API. The mod manager software can handle this

I have already implemented it in Lumafly. I'm here to make the request for making changes to the schema files, as i am not much familiar with these. I also want to know what do you think about this.

[SFGrenade]

personally would probably put it between repository and issues and maybe just call it <ReadMe> but seems nice

[hien-ngo29]

The name <ReadMe> sounds fair enough. That formal name was the one postman wrote for his example of the idea. I though the name was okay so i took it.

But yeah <ReadMe> is shorter and may be better. One vote for it.

[SFGrenade]

completed with #2683