Hi,

This patch contains a reformatting of -march option section in gas 
documentation.

For instance (see 
https://sourceware.org/binutils/docs-2.41/as.html#ARM-Options),
before all the options were on one line:
    For armv8-a:
    +crc: Enables CRC32 Extension. +simd: Enables VFP and NEON for 
Armv8-A. +crypto: Enables
    Cryptography Extensions for Armv8-A, implies +simd. +sb: Enables 
Speculation Barrier
    Instruction for Armv8-A. +predres: Enables Execution and Data 
Prediction Restriction
    Instruction for Armv8-A. +nofp: Disables all FPU, NEON and 
Cryptography Extensions.
    +nocrypto: Disables Cryptography Extensions.

Now, the readability is improved thanks to the itemization of the options:
    For armv8-a:
     +crc: Enables CRC32 Extension.
     +simd: Enables VFP and NEON for Armv8-A.
     +crypto: Enables Cryptography Extensions for Armv8-A, implies +simd.
     +sb: Enables Speculation Barrier Instruction for Armv8-A.
     +predres: Enables Execution and Data Prediction Restriction 
Instruction for Armv8-A.
     +nofp: Disables all FPU, NEON and Cryptography Extensions.
     +nocrypto: Disables Cryptography Extensions.

Ok for binutils-master? I don't have commit access so I need someone to 
commit on my behalf.

Regards,
Matthieu.