[docs]Move llvm-readobj from "Developer Tools" to "Basic Commands"

On the Command Guide page, there are multiple sections with links to the
different documentation pages available for LLVM tools. The "Basic
Tools" section includes tools like llvm-objdump, llvm-nm and so on. The
"Developer Tools" section contains things like FileCheck and lit. This
change moves llvm-readobj into the former block, from the latter.

Reviewed by: MaskRay

Differential Revision: https://reviews.llvm.org/D63011

llvm-svn: 362813

llvm/docs/CommandGuide/index.rst

@@ -35,6 +35,7 @@ Basic Commands
    llvm-dwarfdump
    dsymutil
    llvm-mca
+   llvm-readobj
 
 Debugging Tools
 ~~~~~~~~~~~~~~~
@@ -58,4 +59,3 @@ Developer Tools
    llvm-build
    llvm-exegesis
    llvm-pdbutil
-   llvm-readobj