doc: Fix repo link not in a good format

Signed-off-by: Huaqi Fang <[email protected]>

source/overview/intro.rst

@@ -29,8 +29,13 @@ which works with Nuclei SDK and Nuclei Linux SDK.
 If you have issues in this user guide, please send us an pull request in https://github.com/Nuclei-Software/nuclei-tool-guide repo to help us improve it.
 
 If you have issues in our Nuclei Tools, please send us an issue in this repo or related tool repo to help us improve it.
+
 - Nuclei Studio: https://github.com/Nuclei-Software/nuclei-studio
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 - Nuclei RISC-V Toolchain: https://github.com/riscv-mcu/riscv-gnu-toolchain
+
 - Nuclei OpenOCD: https://github.com/riscv-mcu/riscv-openocd
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 - Nuclei Qemu: https://github.com/riscv-mcu/qemu
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 - Nuclei DLink: https://github.com/nuclei-Software/nuclei-dlink