stall examples: use underscore instead of hyphen

Author: cirosantilli

README.adoc

@@ -17688,9 +17688,10 @@ We can see here that:
 [.....................fdn.pic......r.............................................]-(         120000) 0x004000fc.0 movz x19, #19, #0         [        20]
 ....
 
-====== gem5 event queue DerivO3CPU syscall emulation freestanding example analysis: stall-gain
+[[gem5-event-queue-derivo3cpu-syscall-emulation-freestanding-example-analysis-stall-gain]]
+====== gem5 event queue DerivO3CPU syscall emulation freestanding example analysis: stall_gain
 
-Like <<gem5-event-queue-derivo3cpu-syscall-emulation-freestanding-example-analysis-stall>> but now with an LDR stall: link:userland/arch/aarch64/freestanding/linux/stall-gain.S[].
+Like <<gem5-event-queue-derivo3cpu-syscall-emulation-freestanding-example-analysis-stall>> but now with an LDR stall: link:userland/arch/aarch64/freestanding/linux/stall_gain.S[].
 
 So in this case we see that there were actual potential gains, since the `movz x11` started running immediately. We just stopped at `movz x20` because a new ifetch was needed.
 
@@ -17766,9 +17767,10 @@ Things are still relatively readable because the wrapping aligns them with event
 
 But from this we kind of see the need for: <<gem5-konata-o3-pipeline-viewer>>.
 
-====== gem5 event queue DerivO3CPU syscall emulation freestanding example analysis: stall-hazard4
+[[gem5-event-queue-derivo3cpu-syscall-emulation-freestanding-example-analysis-stall-hazard4]]
+====== gem5 event queue DerivO3CPU syscall emulation freestanding example analysis: stall_hazard4
 
-Like <<gem5-event-queue-derivo3cpu-syscall-emulation-freestanding-example-analysis-stall-gain>> but now with some dependencies after the LDR: link:userland/arch/aarch64/freestanding/linux/stall-hazard4.S[].
+Like <<gem5-event-queue-derivo3cpu-syscall-emulation-freestanding-example-analysis-stall-gain>> but now with some dependencies after the LDR: link:userland/arch/aarch64/freestanding/linux/stall_hazard4.S[].
 
 So in this case the `ic` of dependencies like `add x6, x5, #1` have to wait until the LDR is finished: