markdown lint fixes

docs/install_source.md

@@ -17,7 +17,8 @@
 
 3. Build and install
 
-   #### Unix-like systems
+   **Unix-like systems**
+
    ```sh
    # installs to '/usr/local' by default; sudo may be required, or sudo -E for configured go environments
    $ make install
@@ -26,16 +27,19 @@
    $ make install prefix=/path/to/gh
    ```
 
-   #### Windows
+   **Windows**
+
    ```pwsh
    # build the `bin\gh.exe` binary
    > go run script\build.go
    ```
+
    There is no install step available on Windows.
 
 4. Run `gh version` to check if it worked.
 
-   #### Windows
+   **Windows**
+
    Run `bin\gh version` to check if it worked.
 
 ## Cross-compiling binaries for different platforms
@@ -44,10 +48,12 @@ You can use any platform with Go installed to build a binary that is intended fo
 or CPU architecture. This is achieved by setting environment variables such as GOOS and GOARCH.
 
 For example, to compile the `gh` binary for the 32-bit Raspberry Pi OS:
+
 ```sh
 # on a Unix-like system:
 $ GOOS=linux GOARCH=arm GOARM=7 CGO_ENABLED=0 make clean bin/gh
 ```
+
 ```pwsh
 # on Windows, pass environment variables as arguments to the build script:
 > go run script\build.go clean bin\gh GOOS=linux GOARCH=arm GOARM=7 CGO_ENABLED=0